#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, a;
  cin >> n;
  vector<int> arr(n);
  for (__typeof(n) i = (0) - ((0) > (n)); i != (n) - ((0) > (n));
       i += 1 - 2 * ((0) > (n)))
    cin >> arr[i];
  sort(arr.begin(), arr.end());
  int ans = 0, used = 0, h;
  while (used < n) {
    ans++;
    h = 0;
    for (__typeof(n) i = (0) - ((0) > (n)); i != (n) - ((0) > (n));
         i += 1 - 2 * ((0) > (n))) {
      if (h <= arr[i]) {
        h++;
        used++;
        arr[i] = -1;
      }
    }
  }
  cout << ans;
  return 0;
}
