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.

One day Petya dreamt of a lexicographically k-th permutation of integers from 1 to n. Determine how many lucky numbers in the permutation are located on the positions whose indexes are also lucky numbers.

Input

The first line contains two integers n and k (1 ≤ n, k ≤ 109) — the number of elements in the permutation and the lexicographical number of the permutation.

Output

If the k-th permutation of numbers from 1 to n does not exist, print the single number "-1" (without the quotes). Otherwise, print the answer to the problem: the number of such indexes i, that i and ai are both lucky numbers.

Examples

Input

7 4


Output

1


Input

4 7


Output

1

Note

A permutation is an ordered set of n elements, where each integer from 1 to n occurs exactly once. The element of permutation in position with index i is denoted as ai (1 ≤ i ≤ n). Permutation a is lexicographically smaller that permutation b if there is such a i (1 ≤ i ≤ n), that ai < bi, and for any j (1 ≤ j < i) aj = bj. Let's make a list of all possible permutations of n elements and sort it in the order of lexicographical increasing. Then the lexicographically k-th permutation is the k-th element of this list of permutations.

In the first sample the permutation looks like that:

1 2 3 4 6 7 5

The only suitable position is 4.

In the second sample the permutation looks like that:

2 1 3 4

The only suitable position is 4.
#include <bits/stdc++.h>
using namespace std;
vector<int> kperm(vector<int> A, int k) {
  for (int i = 0; i < A.size(); i++) {
    sort(A.begin() + i, A.end());
    int f = 1;
    for (int j = 1; j < A.size() - i; j++) f *= j;
    swap(A[i + k / f], A[i]);
    k %= f;
  }
  return A;
}
int main() {
  int N, K;
  cin >> N >> K;
  vector<long long> v;
  for (int i = 1; i <= 9; i++) {
    for (int j = 0; j < 1 << i; j++) {
      int x = 0;
      for (int k = 0; k < i; k++) {
        x *= 10;
        x += (j & 1 << k) ? 7 : 4;
      }
      v.push_back(x);
    }
  }
  sort(v.begin(), v.end());
  int result = 0;
  for (int i = 0; i < v.size(); i++) {
    if (v[i] + 13 <= N) {
      result++;
    }
  }
  vector<int> vv;
  for (int i = max(N - 12, 1); i <= N; i++) {
    vv.push_back(i);
  }
  long long fcnt = 1;
  for (int i = 0; i < vv.size(); i++) fcnt *= i + 1;
  if (K > fcnt) {
    cout << "-1" << endl;
    return 0;
  }
  vv = kperm(vv, K - 1);
  for (int i = 0; i < vv.size(); i++) {
    if (binary_search(v.begin(), v.end(), max(N - 12, 1) + i) &&
        binary_search(v.begin(), v.end(), vv[i])) {
      result++;
    }
  }
  cout << result << endl;
}
