#include <bits/stdc++.h>
using namespace std;
const int maxn = 3e5, mod = 1e9 + 7;
multiset<int> q, v;
int n, a[maxn], cnt, ans;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  sort(a + 1, a + n + 1);
  int cur = 1;
  while (cur <= n) {
    ans++;
    int h = 0;
    for (int i = 1; i <= n; i++)
      if (a[i] >= h) {
        h++;
        a[i] = -11;
        cur++;
      }
  }
  cout << ans;
  return 0;
}
