function orient(x1, y1, x2, y2, x3, y3){
    return x2*y3 + x1*y2 + y1*x3 - y1*x2 - y2*x3 - y3*x1;
}


function areIntersecting(x1, y1, x2, y2, x3, y3, x4, y4){
    let o1 = orient(x1, y1, x3, y3, x4, y4);
    let o2 = orient(x2, y2, x3, y3, x4, y4);
    let o3 = orient(x3, y3, x1, y1, x2, y2);
    let o4 = orient(x4, y4, x1, y1, x2, y2);
    if (o1==0 || o2==0 || o3==0 || o4==0){return 0;}
    return ((o1>0)^(o2>0)) && ((o3>0)^(o4>0));
}