#include <bits/stdc++.h>
using namespace std;
int num[105], n;
int main() {
  int cont = 0, ult;
  cin >> n;
  for (int i = 0; i < n; i++) cin >> num[i];
  sort(num, num + n);
  bool check = false;
  int aux, l = 0, steps;
  for (int i = 0; i < n; i++) {
    check = false;
    ult = num[i];
    steps = 1;
    if (ult != -1)
      for (int j = i + 1; j < n; j++) {
        if (steps <= num[j] && num[j] != -1) {
          steps++;
          num[j] = -1;
          check = true;
        }
      }
    if (check) {
      cont++;
      num[i] = -1;
    }
  }
  for (int i = 0; i < n; i++)
    if (num[i] != -1) cont++;
  cout << cont << endl;
  return 0;
}
