#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> vec(n);
  int res = 0;
  for (int i = 0; i < n; i++) cin >> vec[i];
  sort(vec.begin(), vec.end());
  int num = 0;
  bool vis[110] = {0};
  for (int a = 0; a < n; a++) {
    bool ok = 0;
    num = 0;
    for (int i = 0; i < n; i++) {
      if (vis[i]) continue;
      if (vec[i] < num) continue;
      ok = 1;
      num++;
      vis[i] = 1;
    }
    res += ok;
  }
  cout << res << endl;
}
