#include <bits/stdc++.h>
using namespace std;
const int mn = 1e5 + 5;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  int n;
  cin >> n;
  int a[n + 1];
  for (int i = 0; i < n; i += 1) {
    cin >> a[i];
  }
  sort(a, a + n);
  int ag = 0, g = 0, ok = 0;
  while (ok != n) {
    g = 0;
    for (int i = 0; i < n; i += 1) {
      if (a[i] >= g) {
        a[i] = -1;
        g += 1;
        ok += 1;
      }
    }
    ag += 1;
  }
  cout << ag;
  return 0;
}
