#include <iostream>
using namespace std;
 
 
struct point { 
	double x, y; 
};
 
struct point get() {
	struct point a;
	cin >> a.x >> a.y;
	return a;
}
 
double location(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 стороны 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 1 1 1 0 0 0