#include <bits/stdc++.h>
using namespace std;
long long int ans = 0;
vector<long long int> v;
long long int n;
long long int m[111];
void solve() {
  sort(m, m + n);
  bool flag = true;
  while (flag) {
    flag = false;
    long long int now = 0;
    for (int i = 0; i < n; i++) {
      if (m[i] >= now) {
        flag = true;
        now++;
        m[i] = -1;
      }
    }
    if (flag) ans++;
  }
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie();
  cout.tie();
  cin >> n;
  for (int i = 0; i < n; i++) cin >> m[i];
  solve();
  cout << ans << endl;
}
