#include <bits/stdc++.h>
using namespace std;
bool comp(stack<int> s1, stack<int> s2) { return s1.size() < s2.size(); }
int main(int argc, char const *argv[]) {
  int n;
  cin >> n;
  int arr[n];
  int sp[n];
  int wt[n];
  map<int, vector<int> > m;
  for (int i = 0; i < n; i++) {
    wt[i] = 1;
    cin >> arr[i];
    sp[i] = arr[i];
    m[i].push_back(arr[i]);
  }
  sort(arr, arr + n);
  map<int, int> mp;
  int nop = 0;
  for (int i = 0; i < n; i++) {
    if (!mp.count(i)) {
      int crp = arr[i];
      int wt = 1;
      for (int j = i + 1; j < n; j++) {
        if (!mp.count(j) && arr[j] >= wt) {
          wt++;
          mp[j] = 1;
        }
      }
      nop++;
    }
  }
  cout << nop;
  return 0;
}
