Fox and Box Accumulation

#include <cstdio>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
int main()
{
int n,a[110],i,p,q,num;
while(scanf("%d",&n)!=EOF)
{
for(i=1;i<=n;i++)
scanf("%d",&a[i]);
sort(a+1,a+1+n);
q=n;p=0;
while(q)
{
num=0;
for(i=1;i<=n;i++)
{
if(a[i]>=num)
{
num++;
a[i]=-1;
q--;
}
}
p++;
}
printf("%d\n",p);
}
return 0;
}