#include <bits/stdc++.h>
using namespace std;
const int MAXN = 105;
int a[MAXN];
int num[MAXN], top;
int n;
void solve() {
  top = 0;
  memset(num, 0, sizeof num);
  for (int i = (0); i < (n); ++i) scanf("%d", &a[i]);
  sort(a, a + n);
  for (int i = (0); i < (n); ++i) {
    if (a[i] == 0)
      num[++top] = 1;
    else {
      int flag = 0;
      for (int j = (1); j <= (top); ++j)
        if (a[i] >= num[j]) {
          flag = 1;
          ++num[j];
          break;
        }
      if (!flag) num[++top] = 1;
    }
  }
  printf("%d\n", top);
}
int main() {
  while (~scanf("%d", &n)) solve();
  return 0;
}
