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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

public class experiment
{

    static int M = 1_000_000_007;
    static int INF = 1_000_000_000;
    static final FastScanner fs = new FastScanner();

    //variable
    static int N = 100005;
    public static void main(String[] args) throws IOException {

        long L = fs.nextInt();
        long R = fs.nextInt();
        int n = (1<<11)-1;
        long[] dp = new long[n];
        dp[0] = 0;
        long fact = 1;
        for(int i=0;i<n/2;i++) {
            if(i == 1){
                fact *= 10;
            }
            dp[2*i+1] = 4+dp[i]*fact;
            dp[2*i+2] = 7+dp[i]*fact;

        }
        long ans = 0;
        for(int i=1;i<n;i++) {
            if(L>R) break;
            if(dp[i]<L) continue;
            ans += (Math.min(dp[i],R)-L+1)*dp[i];
            L=dp[i]+1;
        }
        System.out.println(ans);
    }

    //function

    static void premutation(int n, ArrayList<Integer> arr,boolean[] chosen) {
        if(arr.size() == n) {

        }else {
            for(int i=1; i<=n; i++) {
                if(chosen[i]) continue;
                arr.add(i);
                chosen[i] = true;
                premutation(n,arr,chosen);
                arr.remove(new Integer(i));
                chosen[i] = false;
            }
        }
    }
    static boolean isPalindrome(char[] c) {
        int n = c.length;
        for(int i=0; i<n/2; i++) {
            if(c[i] != c[n-i-1]) return false;
        }
        return true;
    }
    // Template
    static long nCk(int n, int k) {
        return (modMult(fact(n),fastexp(modMult(fact(n-k),fact(k)),M-2)));
    }

    static long fact (long n) {

        long fact =1;
        for(int i=1; i<=n; i++) {
            fact = modMult(fact,i);
        }
        return fact%M;
    }

    static int modMult(long a,long b) {
        return (int) (a*b%M);
    }

    static long fastexp(long x, int y){
        if(y==1) return x;

        long ans = fastexp(x,y/2);
        if(y%2 == 0) return modMult(ans,ans);

        return modMult(ans,modMult(ans,x));
    }

    static final Random random = new Random();

    static void ruffleSort(int arr[])
    {
        int n = arr.length;
        for(int i=0; i<n; i++)
        {
            int j = random.nextInt(n),temp = arr[j];
            arr[j] = arr[i];
            arr[i] = temp;
        }
        Arrays.sort(arr);
    }


    public static class Pairs implements Comparable<Pairs>
    {
        int value,index;
        Pairs(int value, int index) {
            this.value = value;
            this.index = index;
        }
        public int compareTo(Pairs p) {
            return Integer.compare(this.value,p.value);
        }
    }
}
class FastScanner
{
    BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
    StringTokenizer str = new StringTokenizer("");

    String next() throws IOException
    {
        while(!str.hasMoreTokens())
            str = new StringTokenizer(br.readLine());

        return str.nextToken();
    }

    char nextChar() throws IOException {
        return next().charAt(0);
    }

    int nextInt() throws IOException
    {
        return Integer.parseInt(next());
    }

    float nextfloat() throws IOException
    {
        return Float.parseFloat(next());
    }

    double nextDouble() throws IOException
    {
        return Double.parseDouble(next());
    }
    long nextLong() throws IOException
    {
        return Long.parseLong(next());
    }
    byte nextByte() throws IOException
    {
        return Byte.parseByte(next());
    }
    int [] arrayIn(int n) throws IOException
    {
        int  arr[] = new int[n];
        for(int i=0; i<n; i++)
        {
            arr[i] = nextInt();
        }
        return arr;
    }
}
