#include <iostream>
#include <vector>

using namespace std;

struct P{
  int x, y;
  P operator-(const P& p){
	P q;
	q.x = x - p.x, q.y = y - p.y;
	return q;
  }
};

int cross(P p1, P p2){
  return p1.x*p2.y - p1.y*p2.x;
}

P ps[5];
int main(){
  for(int i=0;i<5;++i)
	cin >> ps[i].x >> ps[i].y;

  vector<bool> ok(5, true);
  for(int i=0;i<5;++i)
	for(int j=i+1;j<5;++j)
	  for(int k=j+1;k<5;++k){
		for(int h=0;h<5;++h){
		  if(i == h || j == h || k == h) continue;
		  int c1 = cross(ps[j]-ps[i],ps[h]-ps[j]);
		  int c2 = cross(ps[k]-ps[j],ps[h]-ps[k]);
		  int c3 = cross(ps[i]-ps[k],ps[h]-ps[i]);
		  if((c1<=0&&c2<=0&&c3<=0)||(c1>=0&&c2>=0&&c3>=0))
			ok[h] = false;
		}
	  }
  int cnt = 0;
  for(int i=0;i<5;++i) if(ok[i]) ++cnt;
  cout << (cnt == 5? "YES": "NO") << endl;

}