#include <bits/stdc++.h>
using namespace std;
int n, pile, cnt, ans = 0;
multiset<int> s;
multiset<int>::iterator it;
int main(void) {
  ios ::sync_with_stdio(0);
  cin.tie(0);
  cin >> n;
  for (int i = 1; i <= n; ++i) {
    cin >> pile;
    s.insert(pile);
  }
  while (s.size()) {
    s.erase(s.begin());
    cnt = 1;
    while ((it = s.lower_bound(cnt)) != s.end()) {
      ++cnt;
      s.erase(it);
    }
    ++ans;
  }
  cout << ans << "\n";
  return 0;
}
