#include <bits/stdc++.h>
using namespace std;
const int maxn = 111;
int n, ans;
int a[maxn];
bool v[maxn];
void Init() {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) scanf("%d", &a[i]);
}
void Work() {
  sort(a + 1, a + 1 + n);
  while (1) {
    int pos = 1;
    while (v[pos] && pos <= n) pos++;
    if (pos == n + 1) break;
    v[pos] = 1;
    int len = 1;
    while (pos <= n) {
      if (a[pos] < len || v[pos]) {
        pos++;
        continue;
      }
      v[pos] = 1;
      len++;
      pos++;
    }
    ans++;
  }
  printf("%d\n", ans);
}
int main() {
  Init();
  Work();
  return 0;
}
