#include<iostream>
using namespace std;

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

     return 0;
}