#include <cstdio>
#include <iostream>
#include <cmath>
#include <cstdlib>

#define P(a) ((a)*(a))
using namespace std;

typedef struct {
    double x;
    double y;
}Point;

double length(Point a,Point b){
    return sqrt(P(b.x-a.x)+P(b.y-a.y));
}

double heron(Point a,Point b,Point c){
    double d,e,f,s;
    d=length(a,b);
    e=length(b,c);
    f=length(c,a);
    s=(d+e+f)/2.0;
    return sqrt(s*(s-d)*(s-e)*(s-f));
}
int main(){
    Point p[3],q;

    while(cin >> p[0].x >> p[0].y >> p[1].x >> p[1].y >> p[2].x >> p[2].y >> q.x >> q.y){
        double Tarea,Carea;
        Tarea=heron(p[0], p[1], p[2]);
        Carea=heron(p[0],p[1],q)+heron(p[1],p[2],q)+heron(p[2],p[0],q);
        if(fabs(Tarea-Carea)<=0.0000000000001) cout << "YES" << endl;
        else cout << "NO" << endl;
    }
    return 0;
}