#include <bits/stdc++.h>
using namespace std;
bool used[200];
int x[200];
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) cin >> x[i];
  sort(x, x + n);
  int ans = 0;
  for (int i = 0; i < n; i++) {
    if (used[i]) continue;
    ans++;
    used[i] = true;
    int remain = 1;
    for (int j = i + 1; j < n; j++) {
      if (used[j]) continue;
      if (x[j] >= remain) {
        used[j] = true;
        remain++;
      }
    }
  }
  cout << ans << endl;
  return 0;
}
