#include <bits/stdc++.h>
using namespace std;
int p[11];
bool used[15];
long long f[15];
vector<int> g;
bool is_good(long long x) {
  if (x < 4) return false;
  while (x > 0) {
    if (x % 10 != 4 && x % 10 != 7) return false;
    x /= 10;
  }
  return true;
}
int main() {
  int n, ans = 0;
  long long k;
  cin >> n >> k;
  f[1] = f[0] = 1;
  for (long long i = 2; i < 15; ++i) f[i] = i * f[i - 1];
  if (n < 14 && k > f[n]) {
    cout << -1;
    return 0;
  }
  while (true) {
    int j = 0;
    p[j]++;
    while (p[j] > 2) {
      p[j] = 0;
      p[++j]++;
    }
    if (p[9] != 0) break;
    bool good = true;
    int cur = 0, mul = 1, cnt = 0;
    for (int i = 0; i < 9; ++i) {
      if (p[i] != 0) {
        cur += mul * (p[i] == 1 ? 4 : 7);
        if (!good) cnt++;
      } else
        good = false;
      mul *= 10;
    }
    if (cnt == 0 && cur > 0 && cur <= n - 14) ans++;
  }
  int len = (n >= 14 ? 14 : n);
  vector<int> perm(len);
  for (int i = 0; i < len; ++i) {
    int dig = -1;
    for (int j = 0; j < len && dig == -1; ++j)
      if (!used[j]) {
        if (k > f[len - i - 1])
          k -= f[len - i - 1];
        else {
          dig = j;
          used[j] = true;
        }
      }
    perm[i] = max(dig, 0) + (n - len) + 1;
  }
  for (int i = 0; i < perm.size(); ++i)
    if (is_good(perm[i]) && is_good(i + (n - len) + 1)) ans++;
  cout << ans;
  return 0;
}
