#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstdlib>
#include<stdio.h>
using namespace std;

int main()
{
 double x1, y1, x2, y2, x3, y3, xp, yp, a, b, c;
 while(cin>>x1>>y1>>x2>>y2>>x3>>y3>>xp>>yp)
 {
	 a = (x2-x1)*(yp-y1)-(y2-y1)*(xp-x1);
     b = (x3-x2)*(yp-y2)-(y3-y2)*(xp-x2);
     c = (x1-x3)*(yp-y3)-(y1-y3)*(xp-x3);
	 if((a>0&&b>0&&c>0)||(a<0&&b<0&&c<0))
		 cout<<"YES"<<endl;
	 else
		 cout<<"NO"<<endl;
 }
 return 0;
}