#include <stdio.h>#include <string.h>#include <stdlib.h>#include <math.h>#include <iostream>typedef struct node{    double x,y;}point;point p1,p2,q1,q2;double result1,result2;double crossProduct(point a,point b1,point b2){    double x1,y1,x2,y2;    x1=a.x-b1.x;    y1=a.y-b1.y;    x2=b2.x-b1.x;    y2=b2.y-b1.y;    return x1*y2-x2*y1;}int main(){    while(1)    {        scanf("%lf%lf",&p1.x,&p1.y);        scanf("%lf%lf",&p2.x,&p2.y);        scanf("%lf%lf",&q1.x,&q1.y);        scanf("%lf%lf",&q2.x,&q2.y);        result1=crossProduct(p1,q1,q2);//注意向量顺序        result2=crossProduct(p2,q2,q1);        printf("%lf  %lf\n",result1,result2);        if(result1*result2>=0)printf("YES\n");//如果叉乘大于0则相交        else printf("NO\n");    }    return 0;}