#include <bits/stdc++.h>
using namespace std;
int n, x[105], used[105], ans = 0;
int main() {
  cin >> n;
  for (int i = 0; i < n; i++) cin >> x[i];
  sort(x, x + n);
  for (int i = 0; i < n; i++) {
    if (!used[i]) {
      used[i] = 1;
      int l = 1;
      for (int j = i + 1; j < n; j++) {
        if (!used[j] && l <= x[j]) {
          used[j] = 1;
          l++;
        }
      }
      ans++;
    }
  }
  cout << ans;
  return 0;
}
