#include<bits/stdc++.h>
using namespace std;
int main()
{
	int T;
	scanf("%d",&T);
	while(T--)
	{
		long long n;
		scanf("%lld",&n);
		if(n%3==0)
		{
			printf("%lld\n",n*n*n/27ll);
			continue;
		}
		if(n%4==0)
		{
			printf("%lld\n",n*n*n/32ll);
			continue;
		}
		printf("-1\n");
	}
	return 0;
}