cin >> i;
long p[i], q[i];
for (int j = 0; j < i; j++)
{
    cin >> p[j];
}
for (int j = 0; j < i; j++)
{
    if (p[j] < 4 || p[j] % 2 == 1)
    {
        cout << "-1"<<endl;
        break;
    }
    if(p[j]%4==0)
    cout<<p[j]*p[j]/16<<endl;
    else cout<<(p[j]/4)*(p[j]/4+1)<<endl; 
}
return 0;