#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
using namespace std;
int main() {
int n, x[105], pl=0, cnt=0, b[105]={0};
vector <int> v;
scanf("%d", &n);
for(int i=0; i<n; i++) scanf("%d", &x[i]);
sort(x, x+n);
while(cnt<n) {
pl++;
for(int i=0; i<n; i++) if(x[i]>=v.size() && b[i]==0) v.push_back(x[i]), b[i]=1, cnt++;
v.clear();
}
printf("%d", pl);
return 0;
}
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