#include <bits/stdc++.h>
using namespace std;
long long P[(100)], g[(100)];
vector<long long> f;
int len;
long long n, m;
bool vis[(100)];
void dfs(long long x, int t) {
  if (t > 10) return;
  f.push_back(x);
  dfs(x * 10ll + 4ll, t + 1);
  dfs(x * 10ll + 7ll, t + 1);
}
bool ok(long long x) {
  while (x > 0ll) {
    if (x % 10ll != 4ll && x % 10ll != 7ll) return false;
    x /= 10ll;
  }
  return true;
}
long long find(long long pos) {
  if (n - pos < (long long)len) {
    int x = len - (int)(n - pos);
    return (long long)g[x] + n - (long long)len;
  }
  return pos;
}
int main() {
  dfs(0ll, 0);
  sort(f.begin(), f.end());
  P[0] = 1ll;
  for (long long i = 1ll; i <= 15ll; ++i) P[i] = P[i - 1] * i;
  cin >> n >> m;
  len = 1;
  while (m > P[len]) len++;
  if (len > n) {
    cout << -1;
    return 0;
  }
  long long tmp = m;
  for (int i = 1; i <= len; ++i) {
    int x = (int)((tmp - 1ll) / P[len - i]), cnt = 0;
    for (int j = 1; j <= len; ++j)
      if (!vis[j]) {
        if (cnt++ >= x) {
          vis[j] = true, g[i] = j;
          break;
        }
      }
    tmp -= (long long)x * P[len - i];
  }
  long long ans = 0ll;
  for (int i = 1; i < f.size(); ++i) {
    if (f[i] > n) break;
    if (ok(find(f[i]))) ans++;
  }
  cout << ans;
  return 0;
}
