#include <bits/stdc++.h>
using namespace std;
vector<pair<string, bool>> dict;
int main() {
  int N;
  vector<pair<int, bool>> arr;
  cin >> N;
  for (int i = 0; i < N; i++) {
    int q = 0;
    cin >> q;
    arr.push_back(make_pair(q, false));
  }
  sort(arr.begin(), arr.end());
  int res = 0;
  for (int i = 0; i < N; i++) {
    if (arr[i].second) continue;
    int sum = 1;
    int cur = i + 1;
    while (1) {
      if (cur >= N) break;
      if ((arr[cur].first >= sum) && !arr[cur].second) {
        sum++;
        arr[cur].second = true;
        cur++;
      } else {
        cur++;
        continue;
      }
    }
    res++;
  }
  cout << res;
  return 0;
}
