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.PrintWriter;
import java.util.*;

public class TP {

    public static PrintWriter out = new PrintWriter(System.out);
    public static Scanner in = new Scanner(System.in);

    public static void main(String[] args) {
        long s = System.currentTimeMillis();
        int t = 1;
//        t = ni();
        while (t-- > 0) solve();
        out.flush();
        tr(System.currentTimeMillis() - s + "ms");
    }

    private static void solve() {
        long l = nl(), r = nl();
        LinkedList<Long> nums = new LinkedList<>();
        rec(nums, 0L);
        Collections.sort(nums);
        long i = 0;
        long sum = 0;
        while (l <= r) {
            long next = next(nums, l);
            i = Math.min(next, r);
            sum += next * (i - l + 1);
            l = i + 1;
        }
        System.out.println(sum);
    }

    private static long next(LinkedList<Long> nums, long l) {
        int id = 0;
        while (nums.get(id) < l) id++;
        return nums.get(id);
    }

    private static void rec(LinkedList<Long> nums, long n) {
        if (n > 7777_777_777L) return;
        nums.add(n);
        rec(nums, 10 * n + 4);
        rec(nums, 10 * n + 7);
    }


    private static long lcm(long a, long b) {
        return a * b / gcd(a, b);
    }

    public static int[][] enumPrimesAndLPF(int n) {
        int[] lpf = new int[n + 1];
        double lu = Math.log(n + 32);

        int tot = 0;
        int[] primes = new int[(int) ((n + 32) / lu + (n + 32) / lu / lu * 1.5)];

        for (int i = 2; i <= n; i++) {
            lpf[i] = i;
        }

        for (int p = 2, tmp; p <= n; p++) {
            if (lpf[p] == p) {
                primes[tot++] = p;
            }
            for (int i = 0; i < tot && primes[i] <= lpf[p] && (tmp = primes[i] * p) <= n; i++) {
                lpf[tmp] = primes[i];
            }
        }

        return new int[][]{Arrays.copyOf(primes, tot), lpf};
    }

    static boolean isPrime(int n) {
        for (int i = 2; i * i <= n; i++) if (n % i == 0) return false;
        return true;
    }

    static boolean sorted(int[] a) {
        for (int i = 0; i < a.length - 1; i++) {
            if (a[i] > a[i + 1]) return false;
        }
        return true;
    }

    public static long gcd(long a, long b) {
        while (b != 0) {
            a %= b;
            long t = a;
            a = b;
            b = t;
        }
        return a;
    }

    private static int ni() {
        return in.nextInt();
    }

    private static String ns() {
        return in.next();
    }

    private static int[] na(int n) {
        int[] a = new int[n];
        for (int i = 0; i < n; i++) a[i] = ni();
        return a;
    }

    private static long[] nal(int n) {
        long[] a = new long[n];
        for (int i = 0; i < n; i++) a[i] = nl();
        return a;
    }

    private static long nl() {
        return in.nextLong();
    }

    private float nf() {
        return in.nextFloat();
    }

    private static double nd() {
        return in.nextDouble();
    }

    public static int[] facs(int n, int[] primes) {
        int[] ret = new int[9];
        int rp = 0;
        for (int p : primes) {
            if (p * p > n) break;
            int i;
            i = 0;
            while (n % p == 0) {
                n /= p;
                i++;
            }
            if (i > 0) ret[rp++] = p;
        }
        if (n != 1) ret[rp++] = n;
        return Arrays.copyOf(ret, rp);
    }

    public static int[] sieveEratosthenes(int n) {
        if (n <= 32) {
            int[] primes = {2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31};
            for (int i = 0; i < primes.length; i++) {
                if (n < primes[i]) {
                    return Arrays.copyOf(primes, i);
                }
            }
            return primes;
        }

        int u = n + 32;
        double lu = Math.log(u);
        int[] ret = new int[(int) (u / lu + u / lu / lu * 1.5)];
        ret[0] = 2;
        int pos = 1;

        int[] isnp = new int[(n + 1) / 32 / 2 + 1];
        int sup = (n + 1) / 32 / 2 + 1;

        int[] tprimes = {3, 5, 7, 11, 13, 17, 19, 23, 29, 31};
        for (int tp : tprimes) {
            ret[pos++] = tp;
            int[] ptn = new int[tp];
            for (int i = (tp - 3) / 2; i < tp << 5; i += tp) ptn[i >> 5] |= 1 << (i & 31);
            for (int j = 0; j < sup; j += tp) {
                for (int i = 0; i < tp && i + j < sup; i++) {
                    isnp[j + i] |= ptn[i];
                }
            }
        }

        // 3,5,7
        // 2x+3=n
        int[] magic = {
                0, 1, 23, 2, 29, 24, 19, 3, 30, 27, 25, 11, 20, 8, 4, 13, 31, 22, 28, 18, 26, 10, 7, 12, 21,
                17, 9, 6, 16, 5, 15, 14
        };
        int h = n / 2;
        for (int i = 0; i < sup; i++) {
            for (int j = ~isnp[i]; j != 0; j &= j - 1) {
                int pp = i << 5 | magic[(j & -j) * 0x076be629 >>> 27];
                int p = 2 * pp + 3;
                if (p > n) break;
                ret[pos++] = p;
                if ((long) p * p > n) continue;
                for (int q = (p * p - 3) / 2; q <= h; q += p) isnp[q >> 5] |= 1 << q;
            }
        }

        return Arrays.copyOf(ret, pos);
    }


    private static final boolean oj = System.getProperty("ONLINE_JUDGE") != null;

    private static void tr(Object... o) {
        if (!oj) System.out.println(Arrays.deepToString(o));
    }
}