#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, t, n, ans, count = 0, a[105], b[105] = {0}, k;
  cin >> n;
  for (i = 0; i < n; i++) {
    cin >> a[i];
    b[i]++;
  }
  sort(a, a + n);
  for (i = 0; i < n; i++) {
    for (j = i + 1; j < n; j++) {
      if (b[i] <= a[j]) {
        b[j] = b[i] + b[j];
        a[j] = a[i] < (a[j] - b[i]) ? a[i] : (a[j] - b[i]);
        b[i] = 0;
        break;
      }
    }
    if (j == n) count++;
  }
  cout << count << endl;
  return 0;
}
