Circle gen

int radius = 500;

if (radius > 0)
{
    for(x=(radius*-1); x<radius; x++)
    {
        for(y=(radius*-1);y<radius;y++)
        {
            if((x*x + y*y) < radius*radius && (x*x + y*y > (radius-1*(radius-1))))
                pixel.setcolor(red);
            else
                pixel.setcolor(blue);
        }
    }
}
else
    print("Error: radius must be positive");