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.lang.reflect.Parameter;
import java.math.*;
import java.util.*;

public class Solution {
    static class FastReader {
        BufferedReader br;
        StringTokenizer st;

        private FastReader() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        String next() {
            while (st == null || !st.hasMoreElements()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

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

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

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

        String nextLine() {
            String str = "";
            try {
                str = br.readLine();
            } catch (IOException e) {
                e.printStackTrace();
            }
            return str;

        }

    }
    static class Pair<U, V> {
        private final U first;       // first field of a Pair
        private final V second;      // second field of a Pair

        // Constructs a new Pair with specified values
        private Pair(U first, V second)
        {
            this.first = first;
            this.second = second;
        }

        @Override
        // Checks specified object is "equal to" current object or not
        public boolean equals(Object o)
        {
            if (this == o)
                return true;

            if (o == null || getClass() != o.getClass())
                return false;

            Pair<?, ?> pair = (Pair<?, ?>) o;

            // call equals() method of the underlying objects
            if (!first.equals(pair.first))
                return false;
            return second.equals(pair.second);
        }

        @Override
        // Computes hash code for an object to support hash tables
        public int hashCode()
        {
            // use hash codes of the underlying objects
            return 31 * first.hashCode() + second.hashCode();
        }

        @Override
        public String toString()
        {
            return "(" + first + ", " + second + ")";
        }

        // Factory method for creating a Typed Pair immutable instance
        public static <U, V> Pair <U, V> of(U a, V b)
        {
            // calls private constructor
            return new Pair<>(a, b);
        }
    }

    public static void main(String[] args) throws IOException {
        FastReader in = new FastReader();
        PrintWriter out = new PrintWriter(System.out);
        long l=in.nextLong();
        long r=in.nextLong();
        ArrayList<Long> ar= new ArrayList<>();
        PriorityQueue<Long> queue= new PriorityQueue<>();
        queue.add(0L);
        while(true){
            long t= queue.poll();
            if(t>4444444444L){
                break;
            }
            else {
                ar.add(t);
            }
            queue.add(t*10+4);
            queue.add(t*10+7);
        }
        ar.add(l);
        Collections.sort(ar);
        int i=0;
        while(true){
            if(ar.get(i) ==l){
                break;
            }
            i++;
        }
        int j=0;
        while(true){
            if(ar.get(j)>r){
                break;
            }
            j++;
        }
        j--;
        long sum=0;
        sum+=ar.get(i+1);
        for(;i<j;i++){
            sum+=(ar.get(i+1)-ar.get(i))*ar.get(i+1);
        }
        sum+= (r-ar.get(j))*ar.get(j+1);
        out.println(sum);
        out.flush();
        out.close();
    }
}