#include <bits/stdc++.h>
using namespace std;
multiset<int> S;
multiset<int>::iterator it;
int main() {
  int n, x, res = 0;
  scanf("%d", &n);
  for (int i = 0; i < n; ++i) scanf("%d", &x), S.insert(x);
  while (!S.empty()) {
    ++res;
    int cur = *S.begin(), cnt = 1;
    S.erase(S.begin());
    while (!S.empty()) {
      it = S.lower_bound(cnt);
      if (it == S.end()) break;
      ++cnt;
      S.erase(it);
    }
  }
  printf("%d", res);
}
