Petya loves lucky numbers. Everybody knows that lucky numbers are positive integers whose decimal representation contains only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

Let next(x) be the minimum lucky number which is larger than or equals x. Petya is interested what is the value of the expression next(l) + next(l + 1) + ... + next(r - 1) + next(r). Help him solve this problem.

Input

The single line contains two integers l and r (1 ≤ l ≤ r ≤ 109) — the left and right interval limits.

Output

In the single line print the only number — the sum next(l) + next(l + 1) + ... + next(r - 1) + next(r).

Please do not use the %lld specificator to read or write 64-bit integers in C++. It is preferred to use the cin, cout streams or the %I64d specificator.

Examples

Input

2 7


Output

33


Input

7 7


Output

7

Note

In the first sample: next(2) + next(3) + next(4) + next(5) + next(6) + next(7) = 4 + 4 + 4 + 7 + 7 + 7 = 33

In the second sample: next(7) = 7


import java.awt.Point;
import java.io.*;
import java.math.BigInteger;
import java.util.*;

import static java.lang.Math.*;

public class C implements Runnable{
    
    final boolean ONLINE_JUDGE = System.getProperty("ONLINE_JUDGE")!=null;
    BufferedReader in;
    PrintWriter out;
    StringTokenizer tok = new StringTokenizer("");
    
    void init() throws FileNotFoundException{
        if (ONLINE_JUDGE){
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
        }else{
            in = new BufferedReader(new FileReader("input.txt"));
            out = new PrintWriter("output.txt");
        }
    }
    
    String readString() throws IOException{
        while(!tok.hasMoreTokens()){
            tok = new StringTokenizer(in.readLine());
        }
        return tok.nextToken();
    }
    
    int readInt() throws IOException{
        return Integer.parseInt(readString());
    }
    
    long readLong() throws IOException{
        return Long.parseLong(readString());
    }
    
    double readDouble() throws IOException{
        return Double.parseDouble(readString());
    }
    
    public static void main(String[] args){
        new Thread(null, new C(), "", 256 * (1L << 20)).start();
    }
    
    public void run(){
        try{
            long t1 = System.currentTimeMillis();
            init();
            solve();
            out.close();
            long t2 = System.currentTimeMillis();
            System.err.println("Time = "+(t2-t1));
        }catch (Exception e){
            e.printStackTrace(System.err);
            System.exit(-1);
        }
    }
    
    void solve() throws IOException{
        long l = readInt();
        long r = readInt();
        long count = 0;
        for (int len = 0; len < 11; len++){
            for (int i = 0; i < (1 << len); i++){
                long x = get(i, len);
                if (r <= x){
                    count += (r - l + 1) * x;
                    out.print(count);
                    return;
                }
                if (l <= x){
                    count += (x - l + 1) * x;
                    l = x + 1;
                }
            }
        }
    }
    
    long get(int i, int len){
        long res = 0;
        long p = 1;
        for (int j = 0; j < len; j++){
            res += p * (((1 << j) & i) == 0? 4: 7);
            p *= 10;
        }
        return res;
    }
    
    static public class Utils {
        
        private Utils() {}
        
        public static void swap(int x, int y){
            x ^= y;
            y ^= x;
            x ^= y;
        }

        public static long mergeSort(int[] a) { // возвращает кол-во инверсий в исходном массиве
            return mergeSort(a, 0, a.length - 1);
        }

        private static long mergeSort(int[] a, int leftIndex, int rightIndex) {
            final int MAGIC_VALUE = 50;
            if (leftIndex < rightIndex) {
                if (rightIndex - leftIndex <= MAGIC_VALUE) {
                    return insertionSort(a, leftIndex, rightIndex);
                } else {
                    int middleIndex = (leftIndex + rightIndex) / 2;
                    return mergeSort(a, leftIndex, middleIndex) +
                    mergeSort(a, middleIndex + 1, rightIndex) +
                    merge(a, leftIndex, middleIndex, rightIndex);
                }
            }
            return 0;
        }

        private static long merge(int[] a, int leftIndex, int middleIndex, int rightIndex) {
            int length1 = middleIndex - leftIndex + 1;
            int length2 = rightIndex - middleIndex;
            int[] leftArray = new int[length1+1];
            int[] rightArray = new int[length2+1];
            System.arraycopy(a, leftIndex, leftArray, 0, length1);
            System.arraycopy(a, middleIndex + 1, rightArray, 0, length2);
            leftArray[length1] = rightArray[length2] = Integer.MAX_VALUE;
            long res = 0;
            for (int k = leftIndex, i = 0, j = 0; k <= rightIndex; k++) {
                if (leftArray[i] > rightArray[j]){
                    a[k] = rightArray[j++];
                    res += length1 - i;
                }else a[k] = leftArray[i++];
            }
            return res;
        }

        private static long insertionSort(int[] a, int leftIndex, int rightIndex) {
            long res = 0;
            for (int i = leftIndex + 1; i <= rightIndex; i++) {
                int current = a[i];
                int j = i - 1;
                while (j >= leftIndex && a[j] > current) {
                    a[j + 1] = a[j];
                    j--;
                    res++;
                }
                a[j + 1] = current;
            }
            return res;
        }
        
        public static int median(int[] a){
            return select(a, 0, a.length - 1, a.length / 2 - 1);
        }
        
        public static int select(int[] a, int i){
            return select(a, 0, a.length - 1, i);
        }
        
        private static int select(int[] a, int l, int r, int i){
            if (l == r) return a[l];
            int len = (r - l) / 5 + 1;
            int[] x = new int[len];
            for (int j = 0; j < len; j++){
                int leftIndex = l + j * 5;
                int rightIndex = min(leftIndex + 4, r);
                insertionSort(a, leftIndex, rightIndex);
                x[j] = a[(rightIndex+leftIndex)/2];
            }
            int med = median(x);
            int m = partition(a, l, r, med);
            int k = m - l;
            if (i == k) return a[k+l];
            else return i < k? select(a, l, m - 1, i): select(a, m + 1, r, i - k - 1);
        }
        
        private static int partition(int[] a, int l, int r, int med){
            int i = l;
            for (int j = l; j <= r; j++){
                if (a[j] < med){
                    swap(a[i++], a[j]);
                }
            }
            return i;
        }
        
        public static int median(int[] x, int[] y){
            return median(x, 0, x.length - 1, y, 0, y.length - 1);
        }
        
        private static int median(int[] x, int xl, int xr, int[] y, int yl, int yr){ // поиск медианы двух отсортированных массивов одинаковой длины
            if (xl == xr){
                int ind = xl + yl;
                for (; ind < x.length - 1 && yl < yr; yl++, ind++);
                return ind == x.length - 1? min(x[xl], y[yl]): max(x[xl], y[yl]);
            }
            if (yl == yr){
                int ind = xl + yl;
                for (; ind < y.length - 1 && xl < xr; xl++, ind++);
                return ind == y.length - 1? min(x[xl], y[yl]): max(x[xl], y[yl]);
            }
            int mdx = (xl + xr) / 2;
            int mdy = (yl + yr) / 2;
            return x[mdx] < y[mdy]? median(x, mdx, xr, y, yl, mdy): median(x, xl, mdx, y, mdy, yr);
        }
        
        public static final int[][] step8 = {{-1, 0}, {1, 0}, {0, -1}, {0, 1},
                                    {-1, -1}, {1, -1}, {-1, 1}, {1, 1}};

        public static final int[][] stepKnight = {{-2, -1}, {-2, 1}, {-1, -2}, {-1, 2},
                                            {1, -2}, {1, 2}, {2, -1}, {2, 1}};
        
        public static long gcd(long a, long b){
            if (a == 0) return b;
            return gcd(b % a, a);
        }
        
        public static long lcm(long a, long b){
            return a / gcd(a, b)*b;
        }

        public static long[] gcdPlus(long a, long b){
            long[] d = new long[3];
            if (a == 0){
                d[0] = b;
                d[1] = 0;
                d[2] = 1;
            }else{
                d = gcdPlus(b % a, a);
                long r = d[1];
                d[1] = d[2] - b/a*d[1];
                d[2] = r;
            }
            return d;
        }
        
        public static long binpow(long a, int n){
            if (n == 0) return 1;
            if ((n & 1) == 0){
                long b = binpow(a, n/2);
                return b*b;
            }else return binpow(a, n - 1)*a;
        }
        
        public static long binpowmod(long a, int n, long m){
            if (m == 1) return 0;
            if (n == 0) return 1;
            if ((n & 1) == 0){
                long b = binpowmod(a, n/2, m);
                return (b*b) % m;
            }else return binpowmod(a, n - 1, m)*a % m;
        }
        
        public static long f(long n, int x, int k){ //Кол-во десятичных чисел (включая 0), содержащих в себе цифры от 0 до k-1
            if (n == 0) return 1;
            long b = binpow(10, x - 1);
            long c = n / b;
            return (c < k? c: k)*binpow(k, x - 1) + (c < k? 1: 0)*f(n % b, x - 1, k);
        }
        
        public static long fib(int n){
            if (n == 0) return 0;
            if ((n & 1) == 0){
                long f1 = fib(n/2 - 1);
                long f2 = fib(n/2 + 1);
                return f2*f2 - f1*f1;
            }else{
                long f1 = fib(n/2);
                long f2 = fib(n/2 + 1);
                return f1*f1 + f2*f2;
            }
        }
        
        public static BigInteger BigFib(int n){
            if (n == 0) return BigInteger.ZERO;
            if ((n & 1) == 0){
                BigInteger f1 = BigFib(n/2 - 1);
                f1 = f1.multiply(f1);
                BigInteger f2 = BigFib(n/2 + 1);
                f2 = f2.multiply(f2);
                return f2.subtract(f1);
            }else{
                BigInteger f1 = BigFib(n/2);
                f1 = f1.multiply(f1);
                BigInteger f2 = BigFib(n/2 + 1);
                f2 = f2.multiply(f2);
                return f2.add(f1);
            }
        }
        
        public static long phi(long n){
            int[] p = new int[1];
            Sieve(p, (int)ceil(sqrt(n)) + 2);
            long phi = 1;
            for (int i = 0; i < p.length; i++){
                long x = 1;
                while (n % p[i] == 0){
                    n /= p[i];
                    x *= p[i];
                }
                phi *= x - x/p[i];
            }
            if (n != 1) phi *= n - 1;
            return phi;
        }
        
        public static boolean IsProbablyPrimeSqrt(long n){
            if (n == 1) return false;
            if ((n & 1) == 0) return (n == 2);
            for (int j = 3; j < sqrt(n) + 1; j += 2){
                if (n % j == 0) return false;
            }
            return true;
        }

        public static void Sieve(int[] p, int n){
            boolean[] b = new boolean[n+1];
            Arrays.fill(b, true);
            b[0] = false;
            b[1] = false;
            long nLong = n;
            int j=0;
            for (int i = 1; i <= n; i++) {
                if (b[i]){
                    j++;
                    if (((long)i)*i <= nLong) {
                        for (int k = i*i; k <= n; k += i) {
                            b[k] = false;
                        }
                    }
                }
            }
            p = new int[j];
            Arrays.fill(p, 0);
            j=0;
            for (int i = 2; i <= n; i++) {
                if (b[i]){
                    p[j]=i;
                    j++;
                }
            }
        }
        
        public static class PointD{
            
            double x, y;
            
            public PointD(double x, double y){
                this.x = x;
                this.y = y;
            }
            
            public double d(PointD p){
                return sqrt(d2(p));
            }
            
            public double d2(PointD p){
                return (x - p.x) * (x - p.x) + (y - p.y) * (y - p.y); 
            }
        }
        
        public static class Point3D{
            
            double x, y, z;
            
            public Point3D(double x, double y, double z){
                this.x = x;
                this.y = y;
                this.z = z;
            }
            
            public double d(Point3D p){
                return sqrt(d2(p));
            }
            
            public double d2(Point3D p){
                return (x - p.x) * (x - p.x) + (y - p.y) * (y - p.y) + (z - p.z) * (z - p.z); 
            }
        }
        
        public static int[][] Palindromes(String s){ // Кол-во всех подстрок - палиндромов в строке
            char[] c = s.toCharArray();
            int n = c.length;
            int[][] d = new int[2][n];
            int l = 0, r = -1;
            for (int i = 0; i < n; i++){
                int j = (i > r? 0: min(d[0][l+r-i+1], r-i+1)) + 1;
                for (; i - j >= 0 && i + j - 1< n && c[i-j] == c[i+j-1]; j++);
                d[0][i] = --j;
                if (i + d[0][i] - 1 > r){
                    r = i + d[0][i] - 1;
                    l = i - d[0][i];
                }
            }
            l = 0;
            r = -1;
            for (int i = 0; i < n; i++){
                int j = (i > r? 0: min(d[1][l+r-i], r-i)) + 1;
                for (; i - j >= 0 && i + j < n && c[i-j] == c[i+j]; j++);
                d[1][i] = --j;
                if (i + d[1][i] > r){
                    r = i + d[1][i];
                    l = i - d[1][i];
                }
            }
            return d;
        }
        
        public static class Permutation {
            
            private int[] a;
            private int n;
            
            public Permutation(int n){
                this.n = n;
                a = new int[n];
                for (int i = 0; i < n; i++){
                    a[i] = i;
                }
            }
            
            public boolean nextPermutation(){ //Пишется с do{}while(nextPermutation(a));
                int i = n - 1;
                for (i = n - 2; i >= 0 && a[i] < a[i+1]; i--);
                if (i == -1) return false;
                int jMin = i + 1;
                for (int j = n - 1; j > i; j--){
                    if (a[i] < a[j] && a[j] < a[jMin]){
                        jMin = j;
                    }
                }
                swap(i, jMin);
                for (int j = 1; j <= (n - i)/2; j++){
                    swap(i + j, n - j);
                }
                return true;
            }
            
            
            public int get(int i){
                return a[i];
            }
            
            private void swap(int i, int j){
                a[i] ^= a[j];
                a[j] ^= a[i];
                a[i] ^= a[j];
            }
        }
        
        public static class Fraction implements Comparable<Fraction>, Cloneable{
            
            public final Fraction FRACTION_ZERO = new Fraction();
            public final Fraction FRACTION_ONE = new Fraction(1);
            public long numerator = 0;
            public long denominator = 1;
            
            public Fraction(){
                numerator = 0;
                denominator = 1;
            }
            
            public Fraction(long numerator){
                this.numerator = numerator;
                denominator = 1;
            }
            
            public Fraction(long numerator, long denominator){
                this.numerator = numerator;
                this.denominator = denominator;
                Cancellation();
            }
            
            public Fraction(double numerator, double denominator, int accuracy){
                this.numerator = (long)(numerator*pow(10,accuracy));
                this.denominator = (long)(denominator*pow(10,accuracy));
                Cancellation();
            }
            
            public Fraction(String s){
                if (s.charAt(0) == '-'){
                    denominator = -1;
                    s = s.substring(1);
                }
                if (s.indexOf("/") != -1){
                    denominator *= Integer.parseInt(s.substring(s.indexOf("/") + 1));
                }
                if (s.indexOf(" ") != -1){
                    numerator = Integer.parseInt(s.substring(0, s.indexOf(" "))) * abs(denominator) + Integer.parseInt(s.substring(s.indexOf(" ") + 1, s.indexOf("/")));
                }else{
                    if (s.indexOf("/") != -1){
                        numerator = Integer.parseInt(s.substring(0, s.indexOf("/")));
                    }else{
                        numerator = Integer.parseInt(s)*abs(denominator);
                    }
                }
                this.Cancellation();
            }
            
            private void Cancellation(){
                long g = gcd(abs(numerator), abs(denominator));
                numerator /= g;
                denominator /= g;
                if (denominator < 0){
                    numerator *= -1;
                    denominator *= -1;
                }
            }
            
            public String toString(){
                String s = "";
                if (numerator == 0){
                    return "0";
                }
                if (numerator < 0){
                    s += "-";
                }
                if (abs(numerator) >= denominator){
                    s += Long.toString(abs(numerator) / denominator) + " ";
                }
                if (abs(numerator) % denominator != 0){
                    s += Long.toString(abs(numerator) % denominator);
                }else{
                    s = s.substring(0, s.length()-1);
                }
                if (denominator != 1){
                    s += "/" + Long.toString(denominator);
                }
                return s;
            }
            
            public Fraction add(Fraction f){
                Fraction fResult = new Fraction();
                fResult.denominator = lcm(denominator, f.denominator);
                fResult.numerator = numerator * fResult.denominator / denominator + f.numerator * fResult.denominator / f.denominator;
                fResult.Cancellation();
                return fResult;
            }
            
            public Fraction subtract(Fraction f){
                Fraction fResult = new Fraction();
                fResult.denominator = lcm(denominator, f.denominator);
                fResult.numerator = numerator * fResult.denominator / denominator - f.numerator * fResult.denominator / f.denominator;
                fResult.Cancellation();
                return fResult;
            }
            
            public Fraction multiply(Fraction f){
                Fraction fResult = new Fraction();
                fResult.numerator = numerator * f.numerator;
                fResult.denominator = denominator * f.denominator;
                fResult.Cancellation();
                return fResult;
            }
            
            public Fraction divide(Fraction f){
                Fraction fResult = new Fraction();
                fResult.numerator = numerator * f.denominator;
                fResult.denominator = denominator * f.numerator;
                fResult.Cancellation();
                return fResult;
            }
            
            @Override
            public int compareTo(Fraction f){
                long g = gcd(denominator, f.denominator);
                long res = numerator * (f.denominator / g) - f.numerator * (denominator / g);
                if (res < 0){
                    return -1;
                }
                if (res > 0){
                    return 1;
                }
                return 0;
            }
            
            public Fraction clone(){
                Fraction fResult = new Fraction(numerator, denominator);
                return fResult;
            }
            
            public Fraction floor(){
                Fraction fResult = this.clone();
                fResult.numerator = (fResult.numerator / fResult.denominator) * fResult.denominator;
                return fResult;
            }
            
            public Fraction ceil(){
                Fraction fResult = this.clone();
                fResult.numerator = (fResult.numerator/fResult.denominator + 1) * fResult.denominator;
                return fResult;
            }
            
            public Fraction binpow(int n){
                if (n==0) return FRACTION_ONE;
                if ((n&1)==0){
                    Fraction f=this.binpow(n/2);
                    return f.multiply(f);
                }else return binpow(n-1).multiply(this);
            }
        }
        
        public static class FenwickTree_1{  //One-dimensional array
            
            private int n;
            private long[] a;
            private long[] tree;
            
            public FenwickTree_1(int n){
                this.n = n;
                tree = new long[n];
                a = new long[n];
            }
            
            public long sum(int xl, int xr){
                return sum(xr) - sum(xl);
            }
            
            private long sum(int x){
                long result = 0;
                for (int i = x; i >= 0; i = (i & (i + 1)) - 1){
                    result += tree[i];
                }
                return result;
            }
            
            public void update(int x, long new_value){
                long delta = new_value - a[x];
                a[x] = new_value;
                for (int i = x; i < n; i = (i | (i + 1))){
                    tree[i] += delta;
                }
            }
        }
        
        public static class FenwickTree_2{  //Two-dimensional array
            
            private int n, m;
            private long[][] a;
            private long[][] tree;
            
            public FenwickTree_2(int n, int m){
                this.n = n;
                this.m = m;
                tree = new long[n][m];
                a = new long[n][m];
            }
            
            public long sum(int xl, int yl, int xr, int yr){
                return sum(xr, yr) - sum(xl - 1, yr) - sum(xr, yl - 1) + sum(xl - 1, yl - 1);
            }
            
            private long sum(int x, int y){
                long result = 0;
                for (int i = x; i >= 0; i = (i & (i + 1)) - 1){
                    for (int j = y; j >= 0; j = (j & (j + 1)) - 1){
                        result+=tree[i][j];
                    }
                }
                return result;
            }
            
            public void update(int x, int y, long new_value){
                long delta = new_value - a[x][y];
                a[x][y] = new_value;
                for (int i = x; i < n; i = (i | (i + 1))){
                    for (int j = y; j < m; j = (j | (j + 1))){
                        tree[i][j] += delta;
                    }
                }
            }
        }
        
        public static class FenwickTree_3{  //Three-dimensional array
            
            private int n, m, l;
            private long[][][] a;
            private long[][][] tree;
            
            public FenwickTree_3(int n, int m, int l){
                this.n = n;
                this.m = m;
                this.l = l;
                tree = new long[n][m][l];
                a = new long[n][m][l];
            }
            
            public long sum(int xl, int yl, int zl, int xr, int yr, int zr){
                return sum(xr, yr, zr) - sum(xl - 1, yr, zr)
                + sum(xl - 1, yr, zl - 1) - sum(xr, yr, zl - 1)
                - sum(xr, yl - 1, zr) + sum(xl - 1, yl - 1, zr)
                - sum(xl - 1, yl - 1, zl - 1) + sum(xr, yl - 1, zl - 1);
            }
            
            private long sum(int x, int y, int z){
                long result = 0;
                for (int i = x; i >= 0; i = (i & (i + 1)) - 1){
                    for (int j = y; j >= 0; j = (j & (j + 1)) - 1){
                        for (int k = z; k >= 0; k = (k & (k + 1)) - 1){
                            result += tree[i][j][k];
                        }
                    }
                }
                return result;
            }
            
            public void update(int x, int y, int z, long new_value){
                long delta = new_value - a[x][y][z];
                a[x][y][z] = new_value;
                for (int i = x; i < n; i = (i | (i + 1))){
                    for (int j = y; j < m; j = (j | (j + 1))){
                        for (int k = z; k < l; k = (k | (k + 1))){
                            tree[i][j][k] += delta;
                        }
                    }
                }
            }
        }
        
        static public class YoungTable{
            
            private long[] table;
            private int n;
            private int countOfElements;
            
            public YoungTable(int nmax) {
                n = (int) floor(sqrt(nmax)) + 1;
                table = new long[n*n];
                Arrays.fill(table, Long.MAX_VALUE);
                countOfElements = 0;
            }
            
            public YoungTable(long[] a){
                n = (int) floor(sqrt(a.length)) + 1;
                table = new long[n*n];
                Arrays.fill(table, Long.MAX_VALUE);
                countOfElements = 0;
                for (int i = 0; i < a.length; i++){
                    put(a[i]);
                }
            }
            
            int size(){
                return countOfElements;
            }
            
            void put(long v) throws ArrayIndexOutOfBoundsException{
                if (countOfElements == table.length) throw new ArrayIndexOutOfBoundsException();
                table[countOfElements] = v;
                YoungTablefyUp(countOfElements++);
            }
            
            private void YoungTablefyUp(int ind){
                int maxInd = ind;
                if (ind >= n && table[maxInd] < table[ind-n]) maxInd = ind - n;
                if (ind % n > 0 && table[maxInd] < table[ind-1]) maxInd = ind - 1;
                if (maxInd != ind){
                    swap(maxInd, ind);
                    YoungTablefyUp(maxInd);
                }
            }
            
            private void swap(int i, int j){
                table[i] ^= table[j];
                table[j] ^= table[i];
                table[i] ^= table[j];
            }
            
            boolean contains(long v){
                int i = n - 1;
                int j = 0;
                int ind = i * n + j;
                boolean exit = true;
                do{
                    exit = true;
                    while (i > 0 && table[ind] > v){
                        i--;
                        ind -= n;
                        exit = false;
                    }
                    while (j < n - 1 && table[ind] < v){
                        j++;
                        ind++;
                        exit = false;
                    }
                }while (!exit);
                return table[ind] == v;
            }
            
            long peek() throws ArrayIndexOutOfBoundsException{
                if (countOfElements == 0) throw new ArrayIndexOutOfBoundsException();
                return table[0];
            }
            
            long poll() throws ArrayIndexOutOfBoundsException{
                if (countOfElements == 0) throw new ArrayIndexOutOfBoundsException();
                long res = table[0];
                table[0] = table[--countOfElements];
                table[countOfElements] = Long.MAX_VALUE;
                YoungTablefyDown(0);
                return res;
            }
            
            private void YoungTablefyDown(int ind){
                int minInd = ind;
                if (ind % n < n - 1 && table[minInd] > table[ind+1]) minInd = ind + 1;
                if (ind / n < n - 1 && table[minInd] > table[ind+n]) minInd = ind + n;
                if (minInd != ind){
                    swap(minInd, ind);
                    YoungTablefyDown(minInd);
                }
            }
            
            void sort(long[] a){
                YoungTable yt = new YoungTable(a);
                for (int i = 0; i < a.length; i++){
                    a[i] = yt.poll();
                }
            }
        }
    }
}

