#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  vector<int> x;
  int ans = 0;
  for (int i = 0; i < n; i++) {
    int t;
    cin >> t;
    x.push_back(t);
  }
  sort(x.begin(), x.end());
  while (!x.empty()) {
    for (int i = 0; i <= n; i++) {
      if (lower_bound(x.begin(), x.end(), i) != x.end()) {
        x.erase(lower_bound(x.begin(), x.end(), i));
      } else {
        ans++;
        break;
      }
    }
  }
  cout << ans << endl;
  return 0;
}
