HDU6298 Maximum Multiple

#include<cmath>
#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
using namespace std;
typedef long long ll;
int main(void)
{
    ll n;
    ll t;
    scanf("%lld",&t);
    while(t--)
    {
        scanf("%lld",&n);
        if(n<3)
            printf("-1\n");
        else
        {
            if(n%3==0)
            {
                printf("%lld\n",n/3*n/3*n/3);
                continue;
            }
            if(n%4==0)
            {
                printf("%lld\n",n/4*n/4*n/2);
            }
            else
                printf("-1\n");
        }
    }
    return 0;
}