#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> t(n);
  bool c[n];
  for (int i = 0; i < n; i++) {
    cin >> t[i];
    c[i] = true;
  }
  sort(t.begin(), t.end());
  int cnt = 0, ans = 0;
  while (cnt != n) {
    int cie = 0;
    for (int i = 0; i < n; i++) {
      if (c[i] && t[i] >= cie) {
        c[i] = false;
        cnt++;
        cie++;
      }
    }
    ans++;
  }
  cout << ans << endl;
  return 0;
}
