#include <bits/stdc++.h>
using namespace std;
int ri() {
  int r;
  cin >> r;
  return r;
}
unsigned int rui() {
  unsigned int r;
  cin >> r;
  return r;
}
long long rl() {
  long long r;
  cin >> r;
  return r;
}
unsigned long long rul() {
  unsigned long long r;
  cin >> r;
  return r;
}
double rd() {
  double r;
  cin >> r;
  return r;
}
string rss() {
  string r;
  cin >> r;
  return r;
}
string rs() {
  string r;
  getline(cin, r);
  return r;
}
vector<string> rvs(int n) {
  assert(n);
  vector<string> r;
  for (int i = 0; i < n; ++i) {
    string s = rs();
    while (s.empty()) s = rs();
    r.push_back(s);
  }
  return r;
}
vector<int> rvi(int n) {
  assert(n);
  vector<int> r;
  for (int i = 0; i < n; ++i) r.push_back(ri());
  return r;
}
vector<unsigned int> rvui(int n) {
  assert(n);
  vector<unsigned int> r;
  for (int i = 0; i < n; ++i) r.push_back(rui());
  return r;
}
vector<long long> rvl(int n) {
  assert(n);
  vector<long long> r;
  for (int i = 0; i < n; ++i) r.push_back(rl());
  return r;
}
vector<unsigned long long> rvul(int n) {
  assert(n);
  vector<unsigned long long> r;
  for (int i = 0; i < n; ++i) r.push_back(rul());
  return r;
}
vector<double> rvd(int n) {
  assert(n);
  vector<double> r;
  for (int i = 0; i < n; ++i) r.push_back(rd());
  return r;
}
int main() {
  int n = ri();
  auto v = rvi(n);
  sort((v).begin(), (v).end());
  size_t cnt = 0;
  while (!v.empty()) {
    ++cnt;
    int cur = 1;
    v.erase(v.begin());
    vector<int>::iterator it;
    while ((it = lower_bound((v).begin(), (v).end(), cur)) != v.end()) {
      ++cur;
      v.erase(it);
    }
  }
  cout << cnt << endl;
  return 0;
}
