#include <complex>
#include <cmath>
#include <iostream>
using namespace std;
typedef complex<double> xy_t;

double x[4], y[4];

double cross_product(xy_t a, xy_t b) { return (conj(a)*b).imag(); }

int main() {
  while (true) {
    for (int i=0; i<4; ++i) cin >> x[i] >> y[i];
    if (!cin) break;
    xy_t a(x[0],y[0]), b(x[1],y[1]), c(x[2],y[2]), p(x[3],y[3]);
    double pab = cross_product(a-p,b-p);
    double pbc = cross_product(b-p,c-p);
    double pca = cross_product(c-p,a-p);

    bool ok = pab*pbc>0 && pbc*pca>0;
    cout << (ok ? "YES" : "NO") << endl;
  }
}
