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
// package com.codeforces.luckysum;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;

public class Main {

   private static final long[] LUCKY =
         new long[] { 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,
               447477474, 447477477, 447477744, 447477747, 447477774,
               447477777, 447744444, 447744447, 447744474, 447744477,
               447744744, 447744747, 447744774, 447744777, 447747444,
               447747447, 447747474, 447747477, 447747744, 447747747,
               447747774, 447747777, 447774444, 447774447, 447774474,
               447774477, 447774744, 447774747, 447774774, 447774777,
               447777444, 447777447, 447777474, 447777477, 447777744,
               447777747, 447777774, 447777777, 474444444, 474444447,
               474444474, 474444477, 474444744, 474444747, 474444774,
               474444777, 474447444, 474447447, 474447474, 474447477,
               474447744, 474447747, 474447774, 474447777, 474474444,
               474474447, 474474474, 474474477, 474474744, 474474747,
               474474774, 474474777, 474477444, 474477447, 474477474,
               474477477, 474477744, 474477747, 474477774, 474477777,
               474744444, 474744447, 474744474, 474744477, 474744744,
               474744747, 474744774, 474744777, 474747444, 474747447,
               474747474, 474747477, 474747744, 474747747, 474747774,
               474747777, 474774444, 474774447, 474774474, 474774477,
               474774744, 474774747, 474774774, 474774777, 474777444,
               474777447, 474777474, 474777477, 474777744, 474777747,
               474777774, 474777777, 477444444, 477444447, 477444474,
               477444477, 477444744, 477444747, 477444774, 477444777,
               477447444, 477447447, 477447474, 477447477, 477447744,
               477447747, 477447774, 477447777, 477474444, 477474447,
               477474474, 477474477, 477474744, 477474747, 477474774,
               477474777, 477477444, 477477447, 477477474, 477477477,
               477477744, 477477747, 477477774, 477477777, 477744444,
               477744447, 477744474, 477744477, 477744744, 477744747,
               477744774, 477744777, 477747444, 477747447, 477747474,
               477747477, 477747744, 477747747, 477747774, 477747777,
               477774444, 477774447, 477774474, 477774477, 477774744,
               477774747, 477774774, 477774777, 477777444, 477777447,
               477777474, 477777477, 477777744, 477777747, 477777774,
               477777777, 744444444, 744444447, 744444474, 744444477,
               744444744, 744444747, 744444774, 744444777, 744447444,
               744447447, 744447474, 744447477, 744447744, 744447747,
               744447774, 744447777, 744474444, 744474447, 744474474,
               744474477, 744474744, 744474747, 744474774, 744474777,
               744477444, 744477447, 744477474, 744477477, 744477744,
               744477747, 744477774, 744477777, 744744444, 744744447,
               744744474, 744744477, 744744744, 744744747, 744744774,
               744744777, 744747444, 744747447, 744747474, 744747477,
               744747744, 744747747, 744747774, 744747777, 744774444,
               744774447, 744774474, 744774477, 744774744, 744774747,
               744774774, 744774777, 744777444, 744777447, 744777474,
               744777477, 744777744, 744777747, 744777774, 744777777,
               747444444, 747444447, 747444474, 747444477, 747444744,
               747444747, 747444774, 747444777, 747447444, 747447447,
               747447474, 747447477, 747447744, 747447747, 747447774,
               747447777, 747474444, 747474447, 747474474, 747474477,
               747474744, 747474747, 747474774, 747474777, 747477444,
               747477447, 747477474, 747477477, 747477744, 747477747,
               747477774, 747477777, 747744444, 747744447, 747744474,
               747744477, 747744744, 747744747, 747744774, 747744777,
               747747444, 747747447, 747747474, 747747477, 747747744,
               747747747, 747747774, 747747777, 747774444, 747774447,
               747774474, 747774477, 747774744, 747774747, 747774774,
               747774777, 747777444, 747777447, 747777474, 747777477,
               747777744, 747777747, 747777774, 747777777, 774444444,
               774444447, 774444474, 774444477, 774444744, 774444747,
               774444774, 774444777, 774447444, 774447447, 774447474,
               774447477, 774447744, 774447747, 774447774, 774447777,
               774474444, 774474447, 774474474, 774474477, 774474744,
               774474747, 774474774, 774474777, 774477444, 774477447,
               774477474, 774477477, 774477744, 774477747, 774477774,
               774477777, 774744444, 774744447, 774744474, 774744477,
               774744744, 774744747, 774744774, 774744777, 774747444,
               774747447, 774747474, 774747477, 774747744, 774747747,
               774747774, 774747777, 774774444, 774774447, 774774474,
               774774477, 774774744, 774774747, 774774774, 774774777,
               774777444, 774777447, 774777474, 774777477, 774777744,
               774777747, 774777774, 774777777, 777444444, 777444447,
               777444474, 777444477, 777444744, 777444747, 777444774,
               777444777, 777447444, 777447447, 777447474, 777447477,
               777447744, 777447747, 777447774, 777447777, 777474444,
               777474447, 777474474, 777474477, 777474744, 777474747,
               777474774, 777474777, 777477444, 777477447, 777477474,
               777477477, 777477744, 777477747, 777477774, 777477777,
               777744444, 777744447, 777744474, 777744477, 777744744,
               777744747, 777744774, 777744777, 777747444, 777747447,
               777747474, 777747477, 777747744, 777747747, 777747774,
               777747777, 777774444, 777774447, 777774474, 777774477,
               777774744, 777774747, 777774774, 777774777, 777777444,
               777777447, 777777474, 777777477, 777777744, 777777747,
               777777774, 777777777, 4444444444L };

   public static long[] readLongs(BufferedReader x) throws IOException {
      String line = x.readLine();
      String[] strings = line.split(" ");
      long[] res = new long[strings.length];
      for (int i = 0; i < res.length; i++) {
         res[i] = Long.parseLong(strings[i]);
      }
      return res;
   }

   public void execute() throws IOException {
      BufferedReader x = new BufferedReader(new InputStreamReader(System.in));
      long[] vals = readLongs(x);

      BigInteger res = BigInteger.ZERO;
      int start = 0;
      for (int i = 0; i < LUCKY.length; i++) {
         if (LUCKY[i] >= vals[0]) {
            start = i;
            break;
         }
      }

      // System.out.println(start);
      long current = vals[0];
      while (true) {
         // System.out.println(start + " " + LUCKY[start] + " " + current);
         long dif =
               LUCKY[start] > vals[1] ? vals[1] - current + 1 : LUCKY[start]
                     - current + 1;
         res =
               res.add(BigInteger.valueOf(LUCKY[start]).multiply(
                     BigInteger.valueOf(dif)));
         // System.out.println(dif + " " + res);
         if (LUCKY[start] > vals[1]) {
            break;
         }

         current = LUCKY[start] + 1;
         start++;
      }

      PrintWriter out = new PrintWriter(System.out);
      out.println(res.toString());
      out.flush();
      out.close();
   }

   public static void main(String[] args) throws IOException {
      Main t = new Main();

      // for (long i = 477777777; i <= 1000000000L; i++) {
      // char[] s = String.valueOf(i).toCharArray();
      // boolean ok = true;
      // for (int j = 0; j < s.length; j++) {
      // if (s[j] != '4' && s[j] != '7') {
      // ok = false;
      // break;
      // }
      // }
      // if (ok) {
      // System.out.print(i + ",");
      // }
      // }

      t.execute();
   }
}
