#include <bits/stdc++.h>
using namespace std;
int A[110], n, ans;
int main() {
  cin >> n;
  for (int i = 0, x; i < n; ++i) cin >> x, A[x]++;
  int nn = n;
  while (nn) {
    int all(0);
    for (int i = 0; i <= 100; i++) {
      if (A[i]) {
        while (A[i] && all <= i) {
          all++;
          A[i]--;
          nn--;
        }
      }
    }
    ans++;
  }
  cout << ans;
}
