#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
#define vP vectorProduct
#define EPS 1e-9

double vectorProduct(double ax,double ay,double bx,double by){return ax*by-ay*bx;}

int main(){
  double x1,y1,x2,y2,x3,y3,xp,yp;

  while(scanf("%lf %lf %lf %lf %lf %lf %lf %lf",&x1,&y1,&x2,&y2,&x3,&y3,&xp,&yp) != EOF){
    if(vP(x2-x1,y2-y1,xp-x1,yp-y1) + EPS > 0 &&
       vP(x3-x2,y3-y2,xp-x2,yp-y2) + EPS > 0 &&
       vP(x1-x3,y1-y3,xp-x3,yp-y3) + EPS > 0)
      printf("YES\n");
    else printf("NO\n");
  }

  return 0;
}