
#include <iostream>
#include <complex>
#include <cmath>
using namespace std;
typedef complex<double> xy_t;
xy_t P[110];
double dot_product(xy_t a, xy_t b) { return (conj(a)*b).real(); }
double cross_product(xy_t a, xy_t b) { return (conj(a)*b).imag(); }
xy_t projection(xy_t p, xy_t b) { return b*dot_product(p,b)/norm(b); }
int main() {
 double x[4], y[4];
 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>0 && pbc>0 && pca>0) || (pab<0 && pbc<0 && pca<0);
  cout << (ok ? "YES" : "NO") << endl;
 }
}
