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

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

double x[4], y[4];
int main() {
  while (1) {
    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 && pab * pca >= 0);
    cout << (ok ? "YES" : "NO") << endl;
  }
  return 0;
}