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 CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
long long a[10005];
int pos;
void dfs(int L, int l, long long v) {
  if (l == L) {
    a[pos++] = v;
    return;
  }
  dfs(L, l + 1, v * 10 + 4);
  dfs(L, l + 1, v * 10 + 7);
}
long long cal(long long x1, long long y1, long long x2, long long y2) {
  long long x = max(x1, x2);
  long long y = min(y1, y2);
  return y + 1 > x ? y - x + 1 : 0;
}
void solve() {
  long long pl, pr, vl, vr, k;
  scanf("%lld%lld%lld%lld%lld", &pl, &pr, &vl, &vr, &k);
  pos = 1;
  a[0] = 0;
  for (int i = 1; i <= 9; i++) dfs(i, 0, 0);
  a[pos] = 1e15;
  long long ans = 0;
  for (int i = 1; i <= pos - k; i++) {
    ans += cal(a[i - 1] + 1, a[i], pl, pr) *
           cal(a[i + k - 1], a[i + k] - 1, vl, vr);
    if (a[i] > pr) break;
  }
  for (int i = 1; i <= pos - k; i++) {
    ans += cal(a[i - 1] + 1, a[i], vl, vr) *
           cal(a[i + k - 1], a[i + k] - 1, pl, pr);
    if (a[i] > vr) break;
  }
  if (k == 1) {
    for (int i = 1; i <= pos - 1; i++) {
      if (cal(a[i], a[i], pl, pr) && cal(a[i], a[i], vl, vr)) ans--;
    }
  }
  printf("%0.12lf\n", double(ans) / (pr - pl + 1) / (vr - vl + 1));
}
int main() {
  solve();
  return 0;
}