#include <bits/stdc++.h>
using namespace std;
int n, arr[1000];
int main() {
  ios_base::sync_with_stdio(false);
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> arr[i];
  }
  sort(arr, arr + n);
  int last = 0, up, ans = 0;
  int lp = n + 1;
  while (lp--) {
    for (int i = 0; i < n; i++) {
      if (arr[i] >= 0) {
        ans++;
        up = 1;
        arr[i] = -1;
        for (int j = i + 1; j < n; j++) {
          if (arr[j] >= up) {
            up++;
            arr[j] = -1;
          }
        }
      }
    }
  }
  cout << ans << endl;
  return 0;
}
