#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
/**
* Problem: Just Odd Inventions (JOI)
* Complexity: O(N + max(Ai))
*/
int main() {
// Crucial for 5 million inputs
ios::sync_with_stdio(false);
cin.tie(NULL);
int n;
if (!(cin >> n)) return 0;
// Use a frequency array since Ai is very small (1 to 21)
vector<int> freq(22, 0);
for (int i = 0; i < n; i++) {
int a;
cin >> a;
if (a <= 21) freq[a]++;
}
int max_k = 0;
int count_le_v = 0;
// Iterate through all possible necktie lengths v
for (int v = 1; v <= 21; v++) {
count_le_v += freq[v];
// From the logic: count_le_v <= k * v + (k - 1)
// count_le_v <= k * (v + 1) - 1
// count_le_v + 1 <= k * (v + 1)
// k >= (count_le_v + 1) / (v + 1)
int required_k = (count_le_v + 1 + v) / (v + 1);
// Note: (a + b - 1) / b is the formula for ceil(a/b)
// Here: ceil((count_le_v + 1) / (v + 1))
if (required_k > max_k) {
max_k = required_k;
}
}
// The minimum k is 1, even if the math says 0
cout << max(1, max_k) << endl;
return 0;
}
