#include <bits/stdc++.h>
using namespace std;
int main() {
  int x[101];
  int towers = 0;
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) cin >> x[i];
  sort(x, x + n);
  int count = 0;
  while (count < n) {
    int cur = 0;
    for (int i = 0; i < n; i++) {
      if (x[i] >= cur) {
        count++;
        cur++;
        x[i] = -1;
      }
    }
    towers++;
  }
  cout << towers << endl;
  return 0;
}
