#include <bits/stdc++.h>
using namespace std;
int n, K, j;
long long nums[100020];
long long f[16];
int a[16];
int us[16];
bool findN(int x) {
  for (int i = 1; i <= j; i++)
    if (nums[i] == x) return 1;
  return 0;
}
long long nex(long long x) {
  for (int i = 1; i <= j; i++) {
    if (nums[i] > x) return nums[i];
  }
  return nums[j];
}
int main() {
  int i, k, le;
  int ans = 0;
  scanf("%d %d", &n, &K);
  j = 0;
  for (le = 1; le < 10; le++) {
    for (k = 0; k < (1 << le); k++) {
      j++;
      nums[j] = 0;
      for (i = 0; i < le; i++) {
        if (k & (1 << i))
          nums[j] = nums[j] * 10 + 7;
        else
          nums[j] = nums[j] * 10 + 4;
      }
    }
  }
  j++;
  nums[j] = 4444444444LL;
  sort(nums + 1, nums + j + 1);
  ans = 0;
  for (i = 1; i <= j; i++) {
    if (nums[i] + 13 <= n) {
      ans++;
    } else
      break;
  }
  f[0] = 1;
  us[0] = 1;
  for (i = 1; i <= 13; i++) {
    a[i] = i;
    f[i] = f[i - 1] * i;
    us[i] = 0;
  }
  if (n <= 13) {
    if (f[n] < K) {
      printf("-1\n");
      return 0;
    }
  }
  if (f[13] < K) {
    printf("-1\n");
    return 0;
  }
  K--;
  for (i = 1; i <= 13; i++) {
    k = 0;
    while ((long long)k * f[13 - i] <= K) k++;
    k--;
    K = K - f[13 - i] * k;
    for (int l = 1; l <= 13; l++) {
      if (us[l] == 0) {
        if (k == 0) {
          a[i] = l;
          us[l] = 1;
          break;
        }
        k--;
      }
    }
  }
  for (i = 1; i <= 13; i++) {
    if ((findN(a[i] - 13 + n) == 1) && (findN(i - 13 + n) == 1)) {
      ans++;
    }
  }
  cout << ans << endl;
  return 0;
}
