#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, k, n, m = 0, c = 0, ans = 0;
  cin >> n;
  int arr[n];
  for (i = 0; i < n; i++) {
    cin >> arr[i];
  }
  sort(arr, arr + n);
  int vis[n];
  memset(vis, 0, sizeof(vis));
  while (c < n) {
    ans++;
    m = 0;
    for (i = 0; i < n; i++) {
      if (!vis[i] && arr[i] >= m) {
        c++, vis[i] = 1;
        m++;
      }
    }
  }
  cout << ans << endl;
}
