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 static java.util.Arrays.deepToString;
import static java.util.Arrays.equals;

public class Problem {

    static List<Long> generate(int len, String acc1, List<Long> acc2) {
        if(len > 10) {
            return null;
        }
        acc2.add(Long.valueOf(acc1 + "4"));
        generate(len + 1, acc1 + "4", acc2);
        acc2.add(Long.valueOf(acc1 + "7"));
        generate(len + 1, acc1 + "7", acc2);
        if(len == 0) {
            return acc2;
        }
        return null;
    }

    static void solve() throws Exception {
        int l = nextInt();
        int r = nextInt();
        List<Long> range = generate(0, "", new ArrayList<Long>());
        Collections.sort(range);
        long sum = 0;
        int left = -1;
        int right = -1;
        int n = range.size();
        for(int i = 0; i < n; i++) {
            long num = range.get(i);
            if(num >= l) {
                left = i;
                break;
            }
        }
        for(int i = 0; i < n; i++) {
            long num = range.get(i);
            if(num <= r) {
                right = i;
            } else {
                break;
            }
        }
        if(right == -1 || range.get(left) >= r){
            sum = (r - l + 1) * range.get(left);
            out.print(sum);
            return;
        }
        sum += (range.get(left) - l + 1 ) * range.get(left);
        sum += (r - range.get(right)) * range.get(right + 1);
        for(int i = left; i < right; i++) {
            long x = range.get(i);
            long y = range.get(i + 1);
            sum += (y - x) * y;
        }
        out.println(sum);
    }

    static BufferedReader br;
    static StringTokenizer tokenizer;
    static PrintWriter out;

    static void debug(Object... a) {
        System.err.println(deepToString(a));
    }

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

    static String next() throws IOException {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            String line = br.readLine();
            if (line == null) {
                return null;
            }
            tokenizer = new StringTokenizer(line);
        }
        return tokenizer.nextToken();
    }

    static long nextLong() throws IOException {
        return Long.parseLong(next());
    }

    static double nextDouble() throws IOException {
        return Double.parseDouble(next());
    }

    public static void main(String[] args) {
        try {
            File file = new File("input.txt");
            InputStream input = System.in;
            OutputStream output = System.out;
            if (file.canRead()) {
                input = (new FileInputStream(file));
                output = (new PrintStream("output.txt"));
            }
            br = new BufferedReader(new InputStreamReader(input));
            out = new PrintWriter(output);
            solve();
            out.close();
            br.close();
        } catch (Throwable e) {
            e.printStackTrace();
            System.exit(1);
        }
    }
}