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

int main()
{
	double x1, y1, x2, y2, x3, y3, x, y;
	double ax, ay, bx, by;
	double z1, z2, z3; // ベクトルAとベクトルBの外積のz成分
	
	while (cin >> x1 >> y1 >> x2 >> y2 >> x3 >> y3 >> x >> y) {
		ax = x2 - x1;
		ay = y2 - y1;
		bx = x - x1;
		by = y - y1;
		z1 = ax * by - ay * bx;
		
		ax = x3 - x2;
		ay = y3 - y2;
		bx = x - x2;
		by = y - y2;
		z2 = ax * by - ay * bx;
		
		ax = x1 - x3;
		ay = y1 - y3;
		bx = x - x3;
		by = y - y3;
		z3 = ax * by - ay * bx;
		
		if ( ( (z1 > 0) && (z2 > 0) && (z3 > 0) ) || ( (z1 < 0) && (z2 < 0) && (z3 < 0) ) )
			cout << "YES\n";
		else
			cout << "NO\n";
	}
	return 0;
}