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:
import java.io.*;
import java.util.*;
import java.math.BigInteger;

public class Main{
    final boolean isFileIO =  false;
    BufferedReader in;
    PrintWriter out;
    StringTokenizer st = new StringTokenizer("");
    String delim = " ";

    public static void main(String[] args) throws IOException {
        Main m = new Main();
        m.initIO();
        m.solve();
        m.in.close();
        m.out.close();
    }

    public void initIO() throws IOException {
        if(!isFileIO) {
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
        } else {
            in = new BufferedReader(new FileReader("input.txt"));
            out = new PrintWriter("output.txt"); 
        }
    }
  
    String nextToken() throws IOException {
        if(!st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken(delim);
    }

    String readLine() throws IOException {
        return in.readLine();
    }

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

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

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

    class Pair {
        public int i;
        public long j;
        public Pair(int i, long j) {
            this.i = i;
            this.j = j;
        }
    }

    public void solve() throws IOException {
        long pl, pr, vl, vr;
        int k;
        pl = nextLong(); pr = nextLong(); vl = nextLong(); vr = nextLong(); k = nextInt();
        long ans = 0;
        ArrayList<Long> nums = new ArrayList<Long>();
        for(int i = 1; i <= 9; i++) {
            for(int j = 0; j < (1 << i); j++) {
                long num = 0;
                for(int z = 0, p = 1; z < i; z++, p *= 10) {
                    if((j & (1 << z)) == (1 << z)) {
                        num += 7 * p;
                    } else {
                        num += 4 * p;
                    }
                }
                nums.add(num);
            }
        }
        nums.add(4444444444L);
        Collections.sort(nums);
        long left = 1;
        long right = 0;
        long all = (pr - pl + 1) * (vr - vl + 1);
        for(int i = 0; i < nums.size() - k; i++) {
            right = nums.get(i + k) - 1;
            long firstl, firstr, secondl, secondr;
            firstr = firstl = secondr = secondl = 0;
            firstl = inter(pl, pr, left, nums.get(i));
            firstr = inter(pl, pr, nums.get(i + k - 1), right);
            secondl = inter(vl, vr, left, nums.get(i));
            secondr = inter(vl, vr, nums.get(i + k - 1), right);
            long res = firstl * secondr + secondl * firstr;
            if(k == 1) {
                long num = nums.get(i);
                if(num >= pl && num <= pr && num >= vl && num <= vr) {
                    res--;
                }
            }
            ans += res;

            left = nums.get(i) + 1;
        }
        out.println(((double)ans) / all);
    }

    public long inter(long l, long r, long x, long y) {
        if(r < x) {
            return 0;
        }
        if(y < l) {
            return 0;
        }
        return Math.min(r, y) - Math.max(l, x) + 1;
    }

}

class Utils {

    public static long binpow(long a, long exp, long mod) {
        if(exp == 0) {
            return 1;
        }
        if(exp % 2 == 0) {
            long temp = binpow(a, exp / 2, mod);
            return (temp * temp) % mod;
        } else {
            return (binpow(a, exp - 1, mod) * a) % mod;
        }
    }

    public static long inv(long a, long mod) {
        return binpow(a, mod - 2, mod);
    }

    public static long addmod(long a, long b, long mod) {
        return ((a + b) % mod + mod) % mod;
    }

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

    //mul must be < 10^18
    public static long mulmod(long a, long b, long mod) {
        return (a * b + (((a * b) / mod) + 1) * mod) % mod;
    }
}