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 Solution121A {
        
        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 Solution121A().run();
        }
        
        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);
                }
        }
        ArrayList<Long> happiens;
        
        int[] cur =  {4,0,0,0,0,0,0,0,0};
        
        boolean Generate(){
        	int c = 0;
        	do{
        		if(cur[c] == 4){
        			cur[c] = 7;
        			String s = "";
        			for(int i = 8; i >= 0; i--){
        				s += Integer.toString(cur[i]);
        			}
        			happiens.add(Long.parseLong(s));
        			return true;
        		}
        		if(cur[c] == 0){
        			cur[c] = 4;
        			String s = "";
        			for(int i = 8; i >= 0; i--){
        				s += Integer.toString(cur[i]);
        			}
        			happiens.add(Long.parseLong(s));
        			return true;
        		}
        		
        			cur[c] = 4;
        			c++;
        			if(c >= 9){
        				return false;
        			
        		}
        		
        	}while(true);
        }
        
        void solve() throws IOException{
        	long l = readInt();
        	long r = readInt();
        	happiens = new ArrayList<Long>();
        	happiens.add((long) 4);
        	boolean c = true;
        	do{
        		c = Generate();
        	}while(c);
        	long max = Long.parseLong("4444444444");
        	happiens.add(max);
        	long summ = 0;
        	int begin = 0, end = 0;
        	for(int i = 0; i < happiens.size(); i++){
        		if(happiens.get(i) >= l){
        			begin = i;
        			break;
        		}
        	}
        	for(int i = 0; i < happiens.size(); i++){
        		if(happiens.get(i) >= r){
        			end = i;
        			break;
        		}
        	}
        	if(begin == end){
        		summ = (r-l+1)*happiens.get(end);
        		out.println(summ);
        		return;
        	}
        	long curIndex = l;
        	for(int i = begin; i < end; i++){
        		summ += (happiens.get(i) - curIndex + 1)*happiens.get(i);
        		curIndex = happiens.get(i)+1;
        	}
        	summ += (r-curIndex + 1)*happiens.get(end);
        	out.println(summ);
        	
        }
        
        int ModExp(int a, int n, int mod){
        	int res = 1;
        	while (n!=0)
        		if ((n & 1) != 0) {
        			res = (res*a)%mod;
        			--n;
        		}
        		else {
        			a = (a*a)%mod;
        			n >>= 1;
        		}
        	return res;
        }
        
        
        static class Utils {
 
                private Utils() {}
 
                public static void mergeSort(int[] a) {
                        mergeSort(a, 0, a.length - 1);
                }
 
                private static void mergeSort(int[] a, int leftIndex, int rightIndex) {
                        final int MAGIC_VALUE = 50;
                        if (leftIndex < rightIndex) {
                                if (rightIndex - leftIndex <= MAGIC_VALUE) {
                                        insertionSort(a, leftIndex, rightIndex);
                                } else {
                                        int middleIndex = (leftIndex + rightIndex) / 2;
                                        mergeSort(a, leftIndex, middleIndex);
                                        mergeSort(a, middleIndex + 1, rightIndex);
                                        merge(a, leftIndex, middleIndex, rightIndex);
                                }
                        }
                }
 
                private static void merge(int[] a, int leftIndex, int middleIndex, int rightIndex) {
                        int length1 = middleIndex - leftIndex + 1;
                        int length2 = rightIndex - middleIndex;
                        int[] leftArray = new int[length1];
                        int[] rightArray = new int[length2];
                        System.arraycopy(a, leftIndex, leftArray, 0, length1);
                        System.arraycopy(a, middleIndex + 1, rightArray, 0, length2);
                        for (int k = leftIndex, i = 0, j = 0; k <= rightIndex; k++) {
                                if (i == length1) {
                                        a[k] = rightArray[j++];
                                } else if (j == length2) {
                                        a[k] = leftArray[i++];
                                } else {
                                        a[k] = leftArray[i] <= rightArray[j] ? leftArray[i++] : rightArray[j++];
                                }
                        }
                }
 
                private static void insertionSort(int[] a, int leftIndex, int rightIndex) {
                        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--;
                                }
                                a[j + 1] = current;
                        }
                } 
        }
        
       
        
        boolean isPrime(int a){
        	for(int i = 2; i <= sqrt(a); i++)
        		if(a % i == 0) return false;
        	return true;
        }
        
        static double distance(long x1, long y1, long x2, long y2){
        	return Math.sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
        }
        
        static long gcd(long a, long b){
        	if(min(a,b) == 0) return max(a,b);
        	return gcd(max(a, b) % min(a,b), min(a,b));
        }
        
        static long lcm(long a, long b){
        	return a * b /gcd(a, b);
        }
}