#include <bits/stdc++.h>
using std::cerr;
using std::cin;
using std::cout;
using std::endl;
using std::map;
using std::max;
using std::min;
using std::pair;
using std::queue;
using std::set;
using std::sort;
using std::stack;
using std::string;
using std::swap;
using std::to_string;
using std::vector;
string to_string(string s) { return '"' + s + '"'; }
string to_string(char s) { return string(1, s); }
string to_string(const char* s) { return to_string((string)s); }
string to_string(bool b) { return (b ? "true" : "false"); }
template <typename A>
string to_string(A);
template <typename A, typename B>
string to_string(pair<A, B> p) {
  return "(" + to_string(p.first) + ", " + to_string(p.second) + ")";
}
template <typename A>
string to_string(A v) {
  bool f = 1;
  string r = "{";
  for (const auto& x : v) {
    if (!f) r += ", ";
    f = 0;
    r += to_string(x);
  }
  return r + "}";
}
void debug_out() {
  if (false) cerr << endl;
}
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
  if (false) cerr << " " << to_string(H);
  debug_out(T...);
}
inline void fast_io() {
  cin.tie(0);
  std::ios::sync_with_stdio(false);
}
template <typename T>
inline T read() {
  T tmp;
  cin >> tmp;
  return tmp;
}
auto readi = []() { return read<int>(); };
int main() {
  fast_io();
  const int n = readi();
  vector<pair<int, int> > v(n, {0, 1});
  for (auto& i : v) i.first = readi();
  ;
  sort(v.begin(), v.end());
  if (false) cerr << __PRETTY_FUNCTION__ << ":" << 79 << "\t - \t";
  debug_out("v: ", v);
  int cnt = 0;
  for (int i = 0; i < n; ++i) {
    bool placed = false;
    for (int j = i + 1; j < n; ++j) {
      if (v[j].first - v[j].second + 1 >= v[i].second) {
        v[j].second += v[i].second;
        v[j].first = v[i].first;
        placed = true;
        if (false) cerr << __PRETTY_FUNCTION__ << ":" << 89 << "\t - \t";
        debug_out("moved ", i, "over", j, "v[j] = ", v[j]);
        break;
      }
    }
    if (!placed) ++cnt;
  }
  cout << cnt;
  return 0;
}
