#include <bits/stdc++.h>

using namespace std;

typedef vector<int> vi;
typedef pair<int, int> pii;
typedef long long ll;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n)  FOR(i,0,n)

struct P{
    double x, y;
    P() {}
    P(double x, double y) : x(x), y(y){
    }
    P operator + (P p){
        return P(x + p.x, y + p.y);
    }
    P operator - (P p){
        return P(x - p.x, y - p.y);
    }
    P operator * (double d){
        return P(d*x, d*y);
    }
    double dot(P p){ //pとの内積
        return x * p.x + y * p.y;
    }
    double det(P p){ //pとの外積
        return x * p.y - p.x * y;
    }
    double dist(P p){ //pとの距離の2乗
        return (x-p.x)*(x-p.x) + (y-p.y)*(y-p.y);
    }
    //辞書順での比較
    bool operator <(const struct P &e) const{
        return x == e.x? (y < e.y) : x < e.x;
    }
    bool operator >(const struct P &e) const{
        return x == e.x? (y > e.y) : x > e.x;
    }
};

vector<P> convex_hull(P* ps, int n){
    sort(ps, ps + n, [](const P& p, const P& q) -> bool { return p<q;});
    int k = 0;
    vector<P> qs(n*2);

    //下側
    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];
    }
    //下側
    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(){
    int N = 5;
    P ps[5];
    for(int i=0;i<N;i++){
        cin >> ps[i].x >> ps[i].y ;
    }
    auto qs = convex_hull(ps,N);
    if(qs.size() == 5){
        cout << "YES" << endl;
    }else{
        cout << "NO" << endl;
    }
    

    return 0;
}