#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cstdio>
#include <queue>
#include "math.h"
#include <complex>
#include <iomanip>
#include <map>
#define ifor(i,a,b) for (int i=(a);i<(b);i++)
#define rfor(i,a,b) for (int i=(b)-1;i>=(a);i--)
#define rep(i,n) for (int i=0;i<(n);i++)
#define rrep(i,n) for (int i=(n)-1;i>=0;i--)
using namespace std;
typedef long double ld;
typedef complex<double> P;
typedef long long lli;
bool cmp_x(const P&p,const P&q){
  if(p.real()!=q.real())return p.real()<q.real();
  return p.imag()<q.imag();
}
double dot(P a,P b){
  //内積
  return (conj(a)*b).real();
}
double cross(P a,P b){
  //det
  return (conj(a)*b).imag();
}

P projection(P p,P b){
  //bと原点を結ぶ直線に点pを投影 
  return b*dot(p,b)/norm(b);
}
int vex[4]={1,0,-1,0};
int vey[4]={0,1,0,-1};
typedef vector<double> Vec;
typedef vector<int> vec;
typedef vector<Vec> MAT;
typedef vector<vec> mat;

lli MOD=1000000007;
vector<P>convex_hull(P* ps,int n){
  sort(ps,ps+n,cmp_x);
  int k =0;
  vector<P>qs(n*2);
  rep(i,n){
    while(k>1&&cross((qs[k-1]-qs[k-2]),(ps[i]-qs[k-1]))<=0)k--;
    qs[k++] = ps[i];
  }
  for(int i = n-2,t=k;i>=0;i--){
    while(k>t&&cross((qs[k-1]-qs[k-2]),(ps[i]-qs[k-1]))<=0)k--;
    qs[k++]=ps[i];
  }
  qs.resize(k-1);
  return qs;
}
int main(){
  P x[5];
  double a,b;
  rep(i,5){
    cin>>a>>b;
    x[i]=P(a,b);
  }
  vector<P> con= convex_hull(x,5);
  if(con.size()==5)cout<<"YES"<<endl;
  else cout<<"NO"<<endl;

}