#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  int ar[1000];
  for (int i = 0; i < n; i++) scanf("%d", &ar[i]);
  sort(ar, ar + n);
  deque<int> q;
  for (int i = 0; i < n; i++) q.push_back(ar[i]);
  int ans = 0;
  while (!q.empty()) {
    ans++;
    int tp = 0;
    int pos = 0;
    while (pos < q.size()) {
      int f = q[pos];
      if (tp <= f) {
        tp++;
        q.erase(q.begin() + pos, q.begin() + pos + 1);
      } else
        pos++;
    }
  }
  printf("%d", ans);
  return 0;
}
