#include<iostream>
#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;
}