#include <bits/stdc++.h>
using namespace std;
int n;
vector<int> inp;
vector<vector<int> > dip;
void input() {
  cin >> n;
  inp.resize(n);
  for (int i = 0; i < n; ++i) cin >> inp[i];
}
void owp() {
  dip.resize(1);
  dip[0].push_back(inp[0]);
  for (int i = 1; i < n; ++i) {
    int q = dip.size();
    bool b = true;
    for (int j = 0; j < q; ++j)
      if (inp[i] >= dip[j].size()) {
        dip[j].insert(dip[j].begin(), inp[i]);
        b = false;
        break;
      }
    if (b) {
      dip.resize(dip.size() + 1);
      dip[dip.size() - 1].push_back(inp[i]);
    }
  }
}
int main() {
  input();
  sort(inp.begin(), inp.end());
  owp();
  cout << dip.size() << endl;
  return 0;
}
