#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int a[105];
  for (int i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  int vis[105] = {0};
  int ans = 0;
  for (int i = 0; i < n; i++) {
    int pre = -1;
    for (int j = i; j < n; j++) {
      if (vis[j]) continue;
      if (a[j] > pre) {
        vis[j] = 1;
        pre++;
      }
    }
    if (pre != -1) ans++;
  }
  cout << ans << endl;
}
