#include <bits/stdc++.h>
using namespace std;
int n, a[101], c = 1, s, used[101];
int mi(int s2) {
  int minn = 5154541, minnn = -1;
  for (int i = 1; i <= n; i++)
    if (a[i] >= s2 && a[i] < minn && !used[i]) minn = a[i], minnn = i;
  used[minnn] = 1;
  return minnn;
}
bool allused(void) {
  for (int i = 1; i <= n; i++)
    if (!used[i]) return false;
  return true;
}
int main() {
  cin >> n;
  for (int i = 1; i <= n; i++) cin >> a[i];
  sort(a + 1, a + 1 + n);
  while (!allused()) {
    if (mi(s) != -1)
      s++;
    else
      s = 0, c++;
  }
  cout << c << endl;
  return 0;
}
