bool inter(point a,point b,point c,point d)
{
    if(min(a.x, b.x)>max(c.x, d.x)||min(a.y, b.y)>max(c.y, d.y)|| min(c.x, d.x)>max(a.x, b.x)||min(c.y, d.y)>max(a.y, b.y))
    return false;
    return true;
}//跨立实验