#include "bits/stdc++.h"
using namespace std;
#define FOR(i,j,k) for(int (i)=(j);(i)<(int)(k);++(i))
#define rep(i,j) FOR(i,0,j)
#define each(x,y) for(auto &(x):(y))
#define mp make_pair
#define all(x) (x).begin(),(x).end()
#define debug(x) cout<<#x<<": "<<(x)<<endl
#define smax(x,y) (x)=max((x),(y))
#define smin(x,y) (x)=min((x),(y))
#define MEM(x,y) memset((x),(y),sizeof (x))
#define sz(x) (int)(x).size()
typedef long long ll;
typedef pair<int, int> pii;
typedef vector<int> vi;
typedef vector<ll> vll;

#define EPS 1e-8
class V2{
public:
    double x, y;

    V2(){}
    V2(double x_, double y_):x(x_),y(y_){}

    bool operator<(const V2 &p) const{
        return x!=p.x?x<p.x:y<p.y;
    }
    V2 operator+(V2 p) const{
        return V2(add(x,p.x), add(y,p.y));
    }
    V2 operator-(V2 p) const{
        return V2(add(x,-p.x), add(y,-p.y));
    }
    double dist()const{
        return sqrt(x*x+y*y);
    }
private:
    double add(double a, double b)const{
        return abs(a+b)<EPS*(abs(a)+abs(b))?0:a+b;
    }
};
V2 operator *(double k, V2 p){
    p.x *= k;
    p.y *= k;
    return p;
}
double dot(const V2 & a, const V2 &b){
    return a.x*b.x + a.y*b.y;
}
double cross(const V2 &a, const V2 &b){
    return a.x * b.y - a.y * b.x;
}

int ccw(V2 a, V2 b, V2 c) {
    b = b-a; c = c-a;
    if(cross(b, c) > EPS) return +1;
    if(cross(b, c) < -EPS) return -1;
    if(dot(b, c) < -EPS) return +2;
    if (b.dist() < c.dist()) return -2;
    return 0;
}

vector<V2> convexHull(vector<V2> ps){
    int n = (int)ps.size();
    sort(begin(ps), end(ps));
    int k = 0;
    vector<V2> qs(n*2);
    for(int i=0; i<n; ++i){
        while(k > 1 && ccw(qs[k-2], qs[k-1], ps[i]) <= 0) k--;
        qs[k++] = ps[i];
    }
    for(int i=n-2, t=k; i>=0; --i){
        while(k>t && ccw(qs[k-2], qs[k-1], ps[i]) <= 0) k--;
        qs[k++] = ps[i];
    }
    qs.resize(k-1);
    return qs;
}

int main(){
    vector<V2> ps(5);
    rep(i, 5)cin >> ps[i].x >> ps[i].y;
    int num = sz(convexHull(ps));
    if(num == 5)cout << "YES" << endl;
    else cout << "NO" << endl;
}