#include<bits/stdc++.h>
using namespace std;
#define rep(i,n) for(ll i=0;i<n;i++)
#define repl(i,l,r) for(ll i=(l);i<(r);i++)
#define per(i,n) for(ll i=(n)-1;i>=0;i--)
#define perl(i,r,l) for(ll i=r-1;i>=l;i--)
#define fi first
#define se second
#define pb push_back
#define ins insert
#define pqueue(x) priority_queue<x,vector<x>,greater<x>>
#define all(x) (x).begin(),(x).end()
#define CST(x) cout<<fixed<<setprecision(x)
#define rev(x) reverse(x);
using ll=long long;
using vl=vector<ll>;
using vvl=vector<vector<ll>>;
using pl=pair<ll,ll>;
using vpl=vector<pl>;
using vvpl=vector<vpl>;
const ll MOD=1000000007;
const ll MOD9=998244353;
const int inf=1e9+10;
const ll INF=4e18;
const ll dy[8]={-1,0,1,0,1,1,-1,-1};
const ll dx[8]={0,-1,0,1,1,-1,1,-1};
template<class T> inline bool chmin(T& a, T b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
template<class T> inline bool chmax(T& a, T b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}


const double EPS=1e-9;
double add(double a,double b){
    if(abs(a+b)<EPS*(abs(a)+abs(b)))return 0;
    return a+b;
}

struct P{
    double x,y;
    P(){}
    P(double x,double y):x(x),y(y){}
    P operator+(P p) {
        return P(add(x,p.x),add(y,p.y));
    }
    P operator-(P p) {
        return P(add(x,-p.x),add(y,-p.y));
    }
    bool operator<(const P &p) const {
        if(x!=p.x)return x<p.x;
        return y<p.y;
    }
    double det(P p){
        return add(x*p.y,-y*p.x);
    }
    double dot(P p){
        return add(x*p.x,y*p.y);
    }
};
bool cmp_x(const P p,const P q){
    if(p.x!=q.x)return p.x<q.x;
    return p.y<q.y;
}
double dist(P &p,P &q){
    return (p-q).dot(p-q);
}

vector<P> convex_hull(vector<P> ps){//点が一つの時は何も返さない
    sort(all(ps),cmp_x);
    int n=ps.size(),k=0;
    vector<P> qs(2*n);
    for(int i=0;i<n;i++){
        while(k>1&&(qs[k-1]-qs[k-2]).det(ps[i]-qs[k-1])<=0)k--;
        qs[k++]=ps[i];
    }
    for(int i=n-2,t=k;i>=0;i--){
        while(k>t&&(qs[k-1]-qs[k-2]).det(ps[i]-qs[k-1])<=0)k--;
        qs[k++]=ps[i];
    }
    qs.resize(k-1);
    return qs;
}

int main(){
    ll n=5;
    vector<P> v(5);
    rep(i,n){
        cin >> v[i].x >>v[i].y;
    }
    auto ans=convex_hull(v);
    if(ans.size()==5)cout << "YES" <<endl;
    else cout << "NO" <<endl;
}