#include <stdio.h>
#include <math.h>
#define out(x1,y1,x2,y2) x1 * y2 - x2 * y1

int main(void){
	double x[3], y[3], xp, yp;
	int i;
	for(i = 0;i < 3;i++)
		scanf("%lf%lf",&x[i],&y[i]);
	scanf("%lf%lf",&xp,&yp);
	if((out(xp - x[0],yp - y[0],x[1] - x[0],y[1] - y[0]) > 0 && out(xp - x[0],yp - y[0],x[2] - x[0],y[2] - y[0]) > 0 && out(xp - x[1],yp - y[1],x[2] - x[1],y[2] - y[1]) > 0) || (out(xp - x[0],yp - y[0],x[1] - x[0],y[1] - y[0]) < 0 && out(xp - x[0],yp - y[0],x[2] - x[0],y[2] - y[0]) < 0 && out(xp - x[1],yp - y[1],x[2] - x[1],y[2] - y[1]) < 0))
		printf("YES\n");
	else
		printf("NO\n");

	return 0;
}