#include <bits/stdc++.h>
using namespace std;
int n, a[101];
void scan() {
  scanf("%d", &n);
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
  sort(a, a + n);
}
void out() {
  int ans = 0, k = 0, c;
  while (1) {
    c = 0;
    for (int i = 0; i < n; i++) {
      if (a[i] != -1) {
        if (a[i] >= k) {
          ++k;
          a[i] = -1;
        }
      } else if (a[i] == -1)
        ++c;
    }
    if (c == n) break;
    ++ans;
    k = 0;
  }
  cout << ans << '\n';
}
int main() {
  scan();
  out();
  return 0;
}
