#include <bits/stdc++.h>
using namespace std;
const int MAXN = 5070;
const int INF = 0x3f3f3f3f;
const int MOD = 1e9 + 7;
int a[MAXN], b[MAXN];
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
  }
  sort(a, a + n);
  int piles = 0;
  while (1) {
    int x = 0;
    for (int i = 0; i < n; i++) {
      if (!b[i] && x <= a[i]) {
        x++;
        b[i] = 1;
      }
    }
    if (x > 0)
      piles++;
    else
      break;
  }
  cout << piles;
  return 0;
}
