#include <iostream>
#include <math.h>
using namespace std;
double getCross( double x1, double y1, double x2, double y2 )
{
	return x1 * y2 - y1 * x2;
}
int main( void )
{
	double x1, y1, x2, y2, x3, y3, xp, yp;
	while ( cin >> x1 >> y1 >> x2 >> y2>> x3 >> y3 >> xp >> yp )
	{
		double a = getCross( xp-x1, yp-y1, xp-x2, xp-y2 );
		double b = getCross( xp-x2, yp-y2, xp-x3, yp-y3 );
		double c = getCross( xp-x3, yp-y3, xp-x1, yp-y1 );

		if ( a < 0 || b < 0 || c < 0 )
			cout << "NO" << endl;
		else
			cout << "YES" << endl;

	}
	return 0;
}