#include <bits/stdc++.h>
using namespace std;
int piles[105];
int main() {
  int n;
  cin >> n;
  vector<int> A(n);
  for (int i = 0; i < n; ++i) cin >> A[i];
  sort(A.begin(), A.end());
  for (int i = 0; i < n; ++i) {
    bool flag = false;
    for (int j = 0; j <= A[i]; ++j)
      if (piles[j]) {
        --piles[j];
        ++piles[j + 1];
        flag = true;
        break;
      }
    if (!flag) piles[1] += 1;
  }
  int cnt = 0;
  for (int i = 1; i < 105; ++i) cnt += piles[i];
  cout << cnt;
  return 0;
}
