#include<stdio.h>
int main()
{
    double x1,x2,x3,y1,y2,y3,x,y,a1,a2,a3,a;
    while(scanf("%lf %lf %lf %lf %lf %lf %lf %lf",&x1,&y1,&x2,&y2,&x3,&y3,&x,&y)!=EOF)
    {
          a=((x1*(y2-y3))+(x2*(y3-y1))+(x3*(y1-y2)))/2;
     a1=((x1*(y2-y))+(x2*(y-y1))+(x*(y1-y2)))/2;
      a2=((x2*(y3-y))+(x3*(y-y2))+(x*(y2-y3)))/2;
       a3=((x3*(y1-y))+(x1*(y-y3))+(x*(y3-y1)))/2;
  if((a1+a2+a3)==a)
    printf("YES\n");
    else
        printf("NO\n");
    }


    return 0;
}