#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  int n, t, m = 0;
  cin >> n;
  vector<int> s;
  for (int i = 0; i < n; i++) {
    cin >> t;
    s.push_back(t);
  }
  sort(s.begin(), s.end());
  while (true) {
    t = -1;
    for (int i = 0; i < n; i++) {
      if (s[i] != -1 && s[i] >= t + 1) {
        s[i] = -1;
        t++;
      }
    }
    if (t == -1) break;
    m++;
  }
  cout << m << endl;
  return 0;
}
