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.*;
import java.util.*;

import java.math.*;
import java.lang.*;
 
 // Oh, Hello there..!!

public class B implements Runnable {
    
    public void run() {
       	
        InputReader sc = new InputReader(System.in);
        PrintWriter out = new PrintWriter(System.out);
 
        int l = sc.nextInt();
        int r = sc.nextInt();
 
        int len = (""+l).length();
 
        char[] tmp = new char[len]; Arrays.fill(tmp,'4'); String s = new String(tmp);
 
        long ans = 0;
        
        long cur = Long.parseLong(s);
        int i;
        for(i=l;i<=r;i++)
        {   
            while(cur<i)
            {
                s = nextPermutation(s);
                cur = Long.parseLong(s);
            }    
            long ttmm=Math.min(cur,r);
         //   out.println((ttmm-i+1)+"   "+cur);        
            ans += (ttmm-i+1)*cur;
            i = (int)ttmm;
        }
    
        out.println(ans);
        out.close();
    }
 


    static String nextPermutation(String x)
    {
        char[] s = x.toCharArray();
        int i=0;
        for(i=s.length-1;i>=0;i--)
        {
            if(s[i]=='4')
            {
                Arrays.fill(s,i,s.length,'4');
                s[i]='7';
                return new String(s);
            }
        }
        Arrays.fill(s,'4');
        return "4"+new String(s);
    }

//========================================================================

	static class Pair
	{
		int a,b;
		Pair(int aa,int bb)
		{
			a=aa;
			b=bb;
		}
	}
	
	static void sa(int a[],InputReader sc)
	{
		for(int i=0;i<a.length;i++)
		{
			a[i]=sc.nextInt();
		}
	}

	static class PairSort implements Comparator<Pair>
	{
		public int compare(Pair a,Pair b)
		{
			return b.b-a.b;
		}
	}

	static boolean isPrime(long n) 
	{ 
	    if (n <= 1)  return false; 
	    if (n <= 3)  return true; 
	    if (n%2 == 0 || n%3 == 0) return false; 
	  
	    for (long i=5; i*i<=n; i=i+6) 
	        if (n%i == 0 || n%(i+2) == 0)  return false; 
	     return true; 
	}

    static class InputReader {
        private InputStream stream;
        private byte[] buf = new byte[1024];
        private int curChar;
        private int numChars;
        private SpaceCharFilter filter;
        private BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
 
        public InputReader(InputStream stream) {
            this.stream = stream;
        }
       
        public int read() {
            if (numChars==-1)
                throw new InputMismatchException();
           
            if (curChar >= numChars) {
                curChar = 0;
                try {
                    numChars = stream.read(buf);
                }
                catch (IOException e) {
                    throw new InputMismatchException();
                }
               
                if(numChars <= 0)              
                    return -1;
            }
            return buf[curChar++];
        }
     
        public String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return str;
        }
        public int nextInt() {
            int c = read();
           
            while(isSpaceChar(c))
                c = read();
           
            int sgn = 1;
           
            if (c == '-') {
                sgn = -1;
                c = read();
            }
           
            int res = 0;
            do {
                if(c<'0'||c>'9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
           
            return res * sgn;
        }
       
        public long nextLong() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            long res = 0;
           
            do {
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            while (!isSpaceChar(c));
                return res * sgn;
        }
       
        public double nextDouble() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            int sgn = 1;
            if (c == '-') {
                sgn = -1;
                c = read();
            }
            double res = 0;
            while (!isSpaceChar(c) && c != '.') {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, nextInt());
                if (c < '0' || c > '9')
                    throw new InputMismatchException();
                res *= 10;
                res += c - '0';
                c = read();
            }
            if (c == '.') {
                c = read();
                double m = 1;
                while (!isSpaceChar(c)) {
                    if (c == 'e' || c == 'E')
                        return res * Math.pow(10, nextInt());
                    if (c < '0' || c > '9')
                        throw new InputMismatchException();
                    m /= 10;
                    res += (c - '0') * m;
                    c = read();
                }
            }
            return res * sgn;
        }
       
        public String readString() {
            int c = read();
            while (isSpaceChar(c))
                c = read();
            StringBuilder res = new StringBuilder();
            do {
                res.appendCodePoint(c);
                c = read();
            }
            while (!isSpaceChar(c));
           
            return res.toString();
        }
     
        public boolean isSpaceChar(int c) {
            if (filter != null)
                return filter.isSpaceChar(c);
            return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
        }
     
        public String next() {
            return readString();
        }
       
        public interface SpaceCharFilter {
            public boolean isSpaceChar(int ch);
        }
    }

    public static void main(String args[]) throws Exception {
        new Thread(null, new B(),"Main",1<<27).start();
    }
}
