#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long a;
  cin >> a;
  vector<long long> x;
  for (long long i = 0; i < a; i++) {
    long long b;
    cin >> b;
    x.push_back(b);
  }
  bool done[101] = {false};
  sort(x.begin(), x.end());
  long long counter = 0;
  long long ans = 0;
  while (counter != a) {
    long long num = 0;
    for (long long i = 0; i < a; i++) {
      if (x[i] >= num && !done[i]) {
        num++;
        counter++;
        done[i] = true;
      }
    }
    ans++;
  }
  cout << ans << "\n";
  return 0;
}
