#include <iostream>
#include <iomanip>
#include <math.h>
#include <utility>
#include <cstdlib>
using namespace std;

int main(){
	double x[3],y[3],xp,yp;
	cin >> x[0] >> y[0] >> x[1] >> y[1] >> x[2] >> y[2] >> xp >> yp;
	bool ans=true;
	for(int i=0;i<3;i++){
		double gaiseki;
		int k = (i+1)%3;
		double vx,vy,vpx,vpy;
		vx = x[k]-x[i];
		vy = y[k]-y[i];
		vpx = xp-x[i];
		vpy = yp-y[i];
		gaiseki = vx*vpy-vy*vpx;
		if(gaiseki<=0) ans = false;
	}
	if(ans){
		cout << "YES" << endl;
	}else{
		cout << "NO" << endl;
	}

	return 0;
}