#include <stdio.h>
 
struct point { double x, y; };
 
// Читать координаты точки
struct point get() 
{
	struct point a;
	scanf("%lf%lf", &a.x, &a.y); // читаем координаты точки
	return a;
}
 
// Вычисляет положение точки D(xd,yd) относительно прямой AB
double g(struct point a, struct point b, struct point d) 
{
	return (d.x - a.x) * (b.y - a.y) - (d.y - a.y) * (b.x - a.x);
}
 
// Лежат ли точки C и D с одной строны прямой (AB)?
bool f(struct point a, struct point b, struct point c, struct point d) 
{
	return g(a, b, c) * g(a, b, d) >= 0;
}
 
int main() {
	struct point a = get(), b = get(), c = get(), d = get();
	printf(	f(a,b,c,d) && f(b,c,a,d) && f(c,a,b,d) ? "yes" : "no");
	return 0;
}

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0	0	2	0	0	2	5	5
0	0	2	0	0	2	1	1
-1	-1	1	-1	0	1	0	0
-1	-1	1	-1	0	1	1	3
-1	-1	1	-1	0	1	0.5	0
-1	-1	1	-1	0	1	0	1
-2	-2	1	-1	0	1	0	0
-1	-1	1	-1	0	1	2	2