#include <bits/stdc++.h>
#pragma GCC optimize("Ofast")
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  int a[n], vis[n];
  for (int i = 0; i < n; ++i) {
    cin >> a[i];
    vis[i] = 0;
  }
  sort(a, a + n);
  int ans = 0;
  for (int i = 0; i < n; i++) {
    int level = 0, flag = 0;
    ;
    for (int j = 0; j < n; j++) {
      if (!vis[j] && a[j] >= level) {
        vis[j] = 1;
        level++;
        flag = 1;
      }
    }
    if (flag) ans++;
  }
  cout << ans;
  return 0;
}
