#include <bits/stdc++.h>
using namespace std;
int offset[] = {1, 0, -1, 0, 1};
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long int n;
  cin >> n;
  vector<long long int> v(n);
  for (long long int i = 0; i < n; i++) cin >> v[i];
  sort(v.begin(), v.end());
  long long int ans = 0, cnt = 0;
  while (cnt < n) {
    long long int temp = 0;
    for (long long int i = 0; i < n; i++) {
      if (v[i] >= temp) {
        v[i] = -1;
        temp++;
        cnt++;
      }
    }
    ans++;
  }
  cout << ans << "\n";
  return 0;
}
