Problem: Petya loves lucky numbers. We all know that lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

Petya and his friend Vasya play an interesting game. Petya randomly chooses an integer p from the interval [pl, pr] and Vasya chooses an integer v from the interval [vl, vr] (also randomly). Both players choose their integers equiprobably. Find the probability that the interval [min(v, p), max(v, p)] contains exactly k lucky numbers.

Input

The single line contains five integers pl, pr, vl, vr and k (1 ≤ pl ≤ pr ≤ 109, 1 ≤ vl ≤ vr ≤ 109, 1 ≤ k ≤ 1000).

Output

On the single line print the result with an absolute error of no more than 10 - 9.

Examples

Input

1 10 1 10 2


Output

0.320000000000


Input

5 6 8 10 1


Output

1.000000000000

Note

Consider that [a, b] denotes an interval of integers; this interval includes the boundaries. That is, <image>

In first case there are 32 suitable pairs: (1, 7), (1, 8), (1, 9), (1, 10), (2, 7), (2, 8), (2, 9), (2, 10), (3, 7), (3, 8), (3, 9), (3, 10), (4, 7), (4, 8), (4, 9), (4, 10), (7, 1), (7, 2), (7, 3), (7, 4), (8, 1), (8, 2), (8, 3), (8, 4), (9, 1), (9, 2), (9, 3), (9, 4), (10, 1), (10, 2), (10, 3), (10, 4). Total number of possible pairs is 10·10 = 100, so answer is 32 / 100.

In second case Petya always get number less than Vasya and the only lucky 7 is between this numbers, so there will be always 1 lucky number.

Solution (in JAVA):

Solution:
//package codeforces;

import java.io.BufferedReader;
import java.io.Closeable;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.Comparator;
import java.util.HashMap;
import java.util.List;
import java.util.Locale;
import java.util.Map;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.TreeSet;

public class B implements Closeable {
    BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
    PrintWriter writer = new PrintWriter(System.out);
    StringTokenizer stringTokenizer;

    B() throws IOException {
//        reader = new BufferedReader(new FileReader("cycle2.in"));
//        writer = new PrintWriter(new FileWriter("cycle2.out"));
    }

    String next() throws IOException {
        while (stringTokenizer == null || !stringTokenizer.hasMoreTokens()) {
            stringTokenizer = new StringTokenizer(reader.readLine());
        }
        return stringTokenizer.nextToken();
    }

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

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

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

    final int MOD = 1000 * 1000 * 1000 + 9;

    int sum(int a, int b) {
        a += b;
        return a >= MOD ? a - MOD : a;
    }

    int product(int a, int b) {
        return (int) (1l * a * b % MOD);
    }

    @SuppressWarnings("unchecked")
    void solve() throws IOException {
        List<Integer> luckyNumbers = new ArrayList<>();
        int[] luckyDigits = {4, 7};
        for (int length = 1; length < 10; length++) {
            for (int i = 0; i < 1 << length; i++) {
                int x = 0;
                for (int j = 0; j < length; j++) {
                    x *= 10;
                    x += luckyDigits[(i >> j) % 2];
                }
                luckyNumbers.add(x);
            }
        }
        luckyNumbers.add(0);
        luckyNumbers.add(1000 * 1000 * 1000 + 1);
        Collections.sort(luckyNumbers);
        class Utils {
            long intersection(int a1, int a2, int b1, int b2) {
                int d = Math.min(b2, a2) - Math.max(a1, b1) + 1;
                return Math.max(d, 0);
            }
        }
        Utils utils = new Utils();
        int pLo = nextInt(), pHi = nextInt(), vLo = nextInt(), vHi = nextInt(), k = nextInt();
        int pLen = pHi - pLo + 1;
        int vLen = vHi - vLo + 1;
        double answer = 0;
        for (int take = 1; take + k < luckyNumbers.size(); take++) {
            final long l1 = utils.intersection(luckyNumbers.get(take - 1) + 1, luckyNumbers.get(take), pLo, pHi) *
                    utils.intersection(luckyNumbers.get(take + k - 1), luckyNumbers.get(take + k) - 1, vLo, vHi);
            answer += l1;
            final long l2 = utils.intersection(luckyNumbers.get(take - 1) + 1, luckyNumbers.get(take), vLo, vHi) *
                    utils.intersection(luckyNumbers.get(take + k - 1), luckyNumbers.get(take + k) - 1, pLo, pHi);
            answer += l2;
            if(k == 1 && l1 > 0 && l2 > 0) {
                answer -= 1;
            }
        }
        answer /= (1l * pLen * vLen);
        writer.printf("%.10f\n", answer);
    }

    public static void main(String[] args) throws IOException {
        try (B b = new B()) {
            b.solve();
        }
    }

    @Override
    public void close() throws IOException {
        reader.close();
        writer.close();
    }
}