#include <bits/stdc++.h>
int a[101];
using namespace std;
int main() {
  int n;
  for (int i = 0; i < 101; i++) a[i] = 0;
  cin >> n;
  for (int i = 0; i < n; i++) {
    int x;
    cin >> x;
    a[x]++;
  }
  int ans = a[0], rem = 0, slots;
  slots = rem;
  for (int i = 1; i < 101; i++) {
    slots += ans;
    if (a[i] >= slots) {
      a[i] = a[i] - slots;
      slots = 0;
      rem = 0;
      if (a[i] % (i + 1) == 0) {
        ans += a[i] / (i + 1);
        rem = 0;
      } else {
        ans += a[i] / (i + 1) + 1;
        rem = i + 1 - a[i] % (i + 1);
        slots = rem;
      }
    } else {
      slots = slots - a[i];
    }
  }
  cout << ans << endl;
  return 0;
}
