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.PrintWriter;
import java.io.*;
import java.util.StringTokenizer;

/**
 * Created by IntelliJ IDEA.
 * User: Dzianis_Siarheyeu
 * Date: 10/27/11
 * Time: 10:05 AM
 * To change this template use File | Settings | File Templates.
 */


public class TaskC extends Thread {
    private static long[] good = {4,7,44,47,74,77,444,447,474,477,744,747,774,777,4444,4447,4474,4477,4744,4747,4774,4777,7444,7447,7474,7477,7744,7747,7774,7777,44444,44447,44474,44477,44744,44747,44774,44777,47444,47447,47474,47477,47744,47747,47774,47777,74444,74447,74474,74477,74744,74747,74774,74777,77444,77447,77474,77477,77744,77747,77774,77777,444444,444447,444474,444477,444744,444747,444774,444777,447444,447447,447474,447477,447744,447747,447774,447777,474444,474447,474474,474477,474744,474747,474774,474777,477444,477447,477474,477477,477744,477747,477774,477777,744444,744447,744474,744477,744744,744747,744774,744777,747444,747447,747474,747477,747744,747747,747774,747777,774444,774447,774474,774477,774744,774747,774774,774777,777444,777447,777474,777477,777744,777747,777774,777777,4444444,4444447,4444474,4444477,4444744,4444747,4444774,4444777,4447444,4447447,4447474,4447477,4447744,4447747,4447774,4447777,4474444,4474447,4474474,4474477,4474744,4474747,4474774,4474777,4477444,4477447,4477474,4477477,4477744,4477747,4477774,4477777,4744444,4744447,4744474,4744477,4744744,4744747,4744774,4744777,4747444,4747447,4747474,4747477,4747744,4747747,4747774,4747777,4774444,4774447,4774474,4774477,4774744,4774747,4774774,4774777,4777444,4777447,4777474,4777477,4777744,4777747,4777774,4777777,7444444,7444447,7444474,7444477,7444744,7444747,7444774,7444777,7447444,7447447,7447474,7447477,7447744,7447747,7447774,7447777,7474444,7474447,7474474,7474477,7474744,7474747,7474774,7474777,7477444,7477447,7477474,7477477,7477744,7477747,7477774,7477777,7744444,7744447,7744474,7744477,7744744,7744747,7744774,7744777,7747444,7747447,7747474,7747477,7747744,7747747,7747774,7747777,7774444,7774447,7774474,7774477,7774744,7774747,7774774,7774777,7777444,7777447,7777474,7777477,7777744,7777747,7777774,7777777,44444444,44444447,44444474,44444477,44444744,44444747,44444774,44444777,44447444,44447447,44447474,44447477,44447744,44447747,44447774,44447777,44474444,44474447,44474474,44474477,44474744,44474747,44474774,44474777,44477444,44477447,44477474,44477477,44477744,44477747,44477774,44477777,44744444,44744447,44744474,44744477,44744744,44744747,44744774,44744777,44747444,44747447,44747474,44747477,44747744,44747747,44747774,44747777,44774444,44774447,44774474,44774477,44774744,44774747,44774774,44774777,44777444,44777447,44777474,44777477,44777744,44777747,44777774,44777777,47444444,47444447,47444474,47444477,47444744,47444747,47444774,47444777,47447444,47447447,47447474,47447477,47447744,47447747,47447774,47447777,47474444,47474447,47474474,47474477,47474744,47474747,47474774,47474777,47477444,47477447,47477474,47477477,47477744,47477747,47477774,47477777,47744444,47744447,47744474,47744477,47744744,47744747,47744774,47744777,47747444,47747447,47747474,47747477,47747744,47747747,47747774,47747777,47774444,47774447,47774474,47774477,47774744,47774747,47774774,47774777,47777444,47777447,47777474,47777477,47777744,47777747,47777774,47777777,74444444,74444447,74444474,74444477,74444744,74444747,74444774,74444777,74447444,74447447,74447474,74447477,74447744,74447747,74447774,74447777,74474444,74474447,74474474,74474477,74474744,74474747,74474774,74474777,74477444,74477447,74477474,74477477,74477744,74477747,74477774,74477777,74744444,74744447,74744474,74744477,74744744,74744747,74744774,74744777,74747444,74747447,74747474,74747477,74747744,74747747,74747774,74747777,74774444,74774447,74774474,74774477,74774744,74774747,74774774,74774777,74777444,74777447,74777474,74777477,74777744,74777747,74777774,74777777,77444444,77444447,77444474,77444477,77444744,77444747,77444774,77444777,77447444,77447447,77447474,77447477,77447744,77447747,77447774,77447777,77474444,77474447,77474474,77474477,77474744,77474747,77474774,77474777,77477444,77477447,77477474,77477477,77477744,77477747,77477774,77477777,77744444,77744447,77744474,77744477,77744744,77744747,77744774,77744777,77747444,77747447,77747474,77747477,77747744,77747747,77747774,77747777,77774444,77774447,77774474,77774477,77774744,77774747,77774774,77774777,77777444,77777447,77777474,77777477,77777744,77777747,77777774,77777777,444444444,444444447,444444474,444444477,444444744,444444747,444444774,444444777,444447444,444447447,444447474,444447477,444447744,444447747,444447774,444447777,444474444,444474447,444474474,444474477,444474744,444474747,444474774,444474777,444477444,444477447,444477474,444477477,444477744,444477747,444477774,444477777,444744444,444744447,444744474,444744477,444744744,444744747,444744774,444744777,444747444,444747447,444747474,444747477,444747744,444747747,444747774,444747777,444774444,444774447,444774474,444774477,444774744,444774747,444774774,444774777,444777444,444777447,444777474,444777477,444777744,444777747,444777774,444777777,447444444,447444447,447444474,447444477,447444744,447444747,447444774,447444777,447447444,447447447,447447474,447447477,447447744,447447747,447447774,447447777,447474444,447474447,447474474,447474477,447474744,447474747,447474774,447474777,447477444,447477447,447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Long.parseLong("4444444444")};


    public void run() {
        try {
            int l = nextInt();
            int r = nextInt();
            long sum = 0;
            int mul = 0;
            int k = 0;
            for (long i = l; i <= r; ) {
//                if (i>777777777){
//                 long s = r-777777777;
//                    s*= Long.parseLong("4444444444");
//                    sum+=s;
//                    out.print(sum);
//                    return;
//                }
               for (; good[k] < i; ++k){

                }
                sum += good[k] * (Math.min(good[k], r) - i+1);
                i = good[k]+1;
            }
            out.print(sum);


        } catch (Exception ex) {
            ex.printStackTrace();
            out.print(ex.getMessage() + "999");
            System.exit(9999);
        } finally {
            out.flush();
            out.close();
        }
    }


    public static void main(String[] args) {
        new TaskC().run();
    }

    public TaskC() {


        in = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(System.out);
//        try {
////            in = new BufferedReader(new FileReader(new File("input.txt")));
//            out = new PrintWriter(new OutputStreamWriter(new FileOutputStream("output.txt")));
//        } catch (FileNotFoundException ex) {
//            out.print(ex.getMessage());
//            ex.printStackTrace();
//            System.exit(9999);
//        }
        setPriority(Thread.MAX_PRIORITY);


    }

    private BufferedReader in;
    private PrintWriter out;
    private StringTokenizer stringTokenizer;

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

    private double nextDouble() throws IOException {
        return Double.parseDouble(nextToken());
    }

    private long nextLong() throws IOException {
        return Long.parseLong(nextToken());
    }

    private String nextToken() throws IOException {
        if (stringTokenizer == null || !stringTokenizer.hasMoreElements()) {
            stringTokenizer = new StringTokenizer(in.readLine(), "\t\n\r ");
        }
        return stringTokenizer.nextToken();
    }
}

