#include <bits/stdc++.h>
using namespace std;
int mm[105] = {0};
bool vis[105] = {0};
int main() {
  int n, ans = 0, m;
  cin >> n;
  m = n;
  for (int i = 0; i < n; i++) {
    cin >> mm[i];
  }
  sort(mm, mm + n);
  int we = 0;
  while (m) {
    for (int i = 0; i < n; i++) {
      if (!vis[i] && mm[i] >= we) {
        vis[i] = 1;
        we++;
        m--;
      }
    }
    ans++;
    we = 0;
  }
  cout << ans << endl;
  return 0;
}
