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必须指出的是，反射镜和2个人共线是不是障碍，但根据该壁其他情况

#include<cstdio>

#include<iostream>

#include<algorithm>

#include<string.h>

#include<math.h>

using namespace std;

#define point Point

const double eps = 1e-8;

const double PI = acos(-1.0);

double ABS(double x){return x>0?x:-x;}

int sgn(double x){

	if(fabs(x) < eps)return 0;

	if(x < 0)return -1;

	else return 1;

}

struct Point

{

	double x,y;

	void put(){printf("(%.0lf,%.0lf)\n",x,y);}

	Point(){}

	Point(double _x,double _y){

	x = _x;y = _y;

	}

	Point operator -(const Point &b)const{

		return Point(x - b.x,y - b.y);

	}

	//叉积

	double operator ^(const Point &b)const{

		return x*b.y - y*b.x;

	}

	//点积

	double operator *(const Point &b)const{

		return x*b.x + y*b.y;

	}

	//绕原点旋转角度B（弧度值），后x,y的变化

	void transXY(double B){

		double tx = x,ty = y;

		x = tx*cos(B) - ty*sin(B);

		y = tx*sin(B) + ty*cos(B);

	}

};

struct Line

{

Point s,e;

void put(){s.put();e.put();}

Line(){}

Line(Point _s,Point _e)

{

s = _s;e = _e;

}

//两直线相交求交点

//第一个值为0表示直线重合，为1表示平行，为0表示相交,为2是相交

//仅仅有第一个值为2时，交点才有意义

pair<int,Point> operator &(const Line &b)const{

	Point res = s;

	if(sgn((s-e)^(b.s-b.e)) == 0)

	{

	if(sgn((s-b.e)^(b.s-b.e)) == 0)

	return make_pair(0,res);//重合

	else return make_pair(1,res);//平行

	}

	double t = ((s-b.s)^(b.s-b.e))/((s-e)^(b.s-b.e));

	res.x += (e.x-s.x)*t;

	res.y += (e.y-s.y)*t;

	return make_pair(2,res);

}

};

double dist(Point a,Point b){return sqrt((a-b)*(a-b));}

//*推断线段相交

bool inter(Line l1,Line l2)

{

	return

	max(l1.s.x,l1.e.x) >= min(l2.s.x,l2.e.x) &&

	max(l2.s.x,l2.e.x) >= min(l1.s.x,l1.e.x) &&

	max(l1.s.y,l1.e.y) >= min(l2.s.y,l2.e.y) &&

	max(l2.s.y,l2.e.y) >= min(l1.s.y,l1.e.y) &&

	sgn((l2.s-l1.e)^(l1.s-l1.e))*sgn((l2.e-l1.e)^(l1.s-l1.e)) <= 0 &&

	sgn((l1.s-l2.e)^(l2.s-l2.e))*sgn((l1.e-l2.e)^(l2.s-l2.e)) <= 0;

}

point symmetric_point(point p1, point l1, point l2)

{

	point ret;

	if(ABS(l1.x-l2.x)<eps){

		ret.y = p1.y;

		ret.x = 2*l1.x - p1.x;

		return ret;

	}

	if(ABS(l1.y-l2.y)<eps) {

		ret.x = p1.x;

		ret.y = 2*l1.y - p1.y;

		return ret;

	}

	if (l1.x > l2.x - eps && l1.x < l2.x + eps)

	{

	ret.x = (2 * l1.x - p1.x);

	ret.y = p1.y;

	}

	else

	{

	double k = (l1.y - l2.y ) / (l1.x - l2.x);

	ret.x = (2*k*k*l1.x + 2*k*p1.y - 2*k*l1.y - k*k*p1.x + p1.x) / (1 + k*k);

	ret.y = p1.y - (ret.x - p1.x ) / k;

	}

	return ret;

}

bool gongxian(Point a, Point b, Point c){

	return ABS((a.y-b.y)*(a.x-c.x) - (a.y-c.y)*(a.x-b.x))<eps;

}

Point a,b;

Line peo, wal, mir;

bool work(){

//	peo.put(); wal.put();

	if((gongxian(a,mir.s,mir.e)&&gongxian(b,mir.s,mir.e))) {

	//	a.put(); b.put(); mir.put();		puts("共线了");

		return !inter(wal,peo);

	}

	else if(inter(mir,peo))return false;

	if(!inter(wal, peo)) return true;

//	puts("GEGE");

	if(inter(wal,mir))return false;

	Point c = symmetric_point(b,mir.s,mir.e);

	Point d = symmetric_point(a,mir.s,mir.e);

//	c.put(); d.put();

	Line ac, bd;

	ac.s = a, ac.e = c;

	bd.s = b, bd.e = d;

	if(!inter(ac,mir))return false;

	if(!inter(bd,mir))return false;

	if(inter(ac,wal))return false;

	if(inter(bd,wal))return false;

	return true;

}

int main(){

    while(~scanf("%lf %lf",&a.x,&a.y)){

		scanf("%lf %lf",&b.x,&b.y);

		scanf("%lf %lf %lf %lf", &wal.s.x, &wal.s.y, &wal.e.x, &wal.e.y);

		scanf("%lf %lf %lf %lf", &mir.s.x, &mir.s.y, &mir.e.x, &mir.e.y);

		peo.s = a, peo.e = b;

		work()?

puts("YES"):puts("NO");

    }

    return 0;

}