#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> v(n);
  for (int i = 0; i < n; i++) {
    cin >> v[i];
  }
  sort(v.begin(), v.end());
  int used = 0, ans = 0;
  while (used < n) {
    ans++;
    int h = 0;
    for (int i = 0; i < n; i++)
      if (v[i] >= h) {
        v[i] = -1;
        h++;
        used++;
      }
  }
  cout << ans << endl;
}
