#include <cstdio>
#include <cmath>
#include <utility>
using namespace std;

#define x first
#define y second
#define EPS 1e-20

struct vector { double x, y, l; };

int main()
{
    pair<double, double> p[4];

    while (~scanf("%lf %lf", &p->x, &p->y)){
        vector v[3];
        double angle[3];

        for (int i = 1; i < 4; i++) scanf("%lf %lf", &p[i].x, &p[i].y);
        for (int i = 0; i < 3; i++){
            v[i].x = p[i].x - p[3].x;
            v[i].y = p[i].y - p[3].y;
            v[i].l = sqrt(v[i].x * v[i].x + v[i].y * v[i].y);
        }
        for (int i = 0; i < 3; i++){
            double product = v[i].x * v[(i + 1) % 3].x + v[i].y * v[(i + 1) % 3].y;
            angle[i] = acos(product / v[i].l / v[(i + 1) % 3].l) + EPS;
        }

        if (angle[0] + angle[1] + angle[2] == 2 * M_PI){
            puts("YES");
        }
        else {
            puts("NO");
        }
    }

    return 0;
}