#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[n];
  int c[n];
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    c[i] = 0;
  }
  sort(a, a + n);
  int w = 0;
  ;
  for (int i = 0; i < n; i++) {
    if (c[i] == 0) {
      int x = c[i];
      int e = 1;
      w++;
      c[i] = w;
      for (int j = i + 1; j < n; j++) {
        if (a[j] >= e && c[j] == 0) {
          x = a[j];
          c[j] = w;
          e++;
        }
      }
    }
  }
  cout << w << endl;
  return 0;
}
