#include <bits/stdc++.h>
using namespace std;
const double EPS = -1e8;
const double Pi = acos(-1);
bool inline equ(double a, double b) { return fabs(a - b) < EPS; }
const int MAXN = 110;
int n;
vector<int> in;
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n;
  in.resize(n);
  for (int i = (0); i <= (n - 1); i++) cin >> in[i];
  sort((in).begin(), (in).end());
  int acc = 0, ans = 0;
  while ((int)(in).size()) {
    ans++;
    acc = 0;
    for (int i = 0; i < (int)(in).size(); i++)
      if (in[i] >= acc) {
        acc++;
        in.erase(in.begin() + i);
        i--;
      }
  }
  cout << ans << '\n';
}
