#include<iostream>
#include<complex>

using namespace std;

double cross(complex<double> A, complex<double> B){
	return (conj(A)*B).imag();
}

int main(){
	while(true){
		complex<double> Point[3], P;
		double x,y;
		for(int i=0;i<3;i++){
			cin >> x >> y;
			Point[i]={x,y};
		}

		cin >> x >> y;
		P={x,y};

		if(!cin)
			break;

		int sum=0;
		for(int i=0;i<3;i++){
			sum += cross(Point[(i+1)%3]-Point[i], P-Point[i])>0;
		}
		cout << (sum==0||sum==3 ? "Yes":"No") << endl;
	}
	return 0;
}

