#include <bits/stdc++.h>

using namespace std;
using ll = long long;

// vector OA = (x, y)
template <typename T>
struct vec{
    T x, y;

    vec (T xx=0, T yy=0) : x(xx), y(yy) {};
    vec operator-() const {
      return vec(-x, -y);
    }
    vec& operator+=(const vec &w) {
        x += w.x; y += w.y;
        return *this;
    }
    vec& operator-=(const vec &w) {
        x -= w.x; y -= w.y;
        return *this;
    }
    vec operator+(const vec &w) const {
        vec res(*this);
        return res += w;
    }
    vec operator-(const vec &w) const {
        vec res(*this);
        return res-=w;
    }
};

//Inner product of vectors v and w
template <typename T>
T dot(vec<T> v, vec<T> w){
    return v.x * w.x + v.y * w.y;
}

//Outer product of vector v and w
template <typename T>
T outer(vec<T> v, vec<T> w){
    return v.x * w.y - w.x * v.y;
}

//size of triangle ABC
template <typename T>
T heron(vec<T> &a, vec<T> &b, vec<T> &c){
    return abs(outer(b-a, c-a)) / 2;
}

//Convex Hull(Smallest Convex set containing all given vecs)
//Grahum Scan (O(NlogN))
template <typename T>
vector<vec<T>> convex_hull(vector<vec<T>> P){

    sort(P.begin(), P.end(), [](vec<T> &p1, vec<T> &p2) {
        if (p1.x != p2.x) return p1.x < p2.x;
        return p1.y < p2.y;
    });

    int N=P.size(), k=0, t;
    vector<vec<T>> res(N*2);

    for (int i=0; i<N; i++){
        while(k > 1 && outer(res[k-1]-res[k-2], P[i]-res[k-1]) <= 0) k--;
        res[k] = P[i];
        k++;
    }
    t = k;

    for (int i=N-2; i>=0; i--){
        while(k > t && outer(res[k-1]-res[k-2], P[i]-res[k-1]) <= 0) k--;
        res[k] = P[i];
        k++;
    }
    res.resize(k-1);

    return res;
}

//distance between line PQ and point R
template <typename T>
T dist_line_point(vec<T> &p, vec<T> &q, vec<T> &r){
    // ax+by+c=0
    T a = (q.y-p.y), b = (p.x-q.x), c = -p.x*q.y + p.y*q.x;
    cout << a << " " << b << " " << c << endl;
    return abs(a*r.x+b*r.y+c) / sqrt(a*a+b*b);
};

//judge if line AB intersects line CD
template <typename T>
bool intersect(vec<T> &a, vec<T> &b, vec<T> &c, vec<T> &d){
    T s, t;
    s = outer(b-a, c-a);
    t = outer(b-a, d-a);
    if (s == 0 && t == 0){
        if (max(a.x, b.x)<min(c.x, d.x) || max(a.y, b.y)<min(c.y, d.y) || min(a.x, b.x)>max(c.x, d.x) || min(a.y, b.y)>max(c.y, d.y)) return 0;
        else return 1;
    }
    if ((s > 0 && t > 0) || (s < 0 && t < 0)) return 0;
    s = outer(d-c, a-c);
    t = outer(d-c, b-c);
    if ((s > 0 && t > 0) || (s < 0 && t < 0)) return 0;

    return 1;
}

int main(){

    ll x, y;
    vector<vec<ll>> p(5), q;
    for (int i=0; i<5; i++){
        cin >> x >> y;
        p[i] = vec(x, y);
    }

    q = convex_hull(p);
    cout << (q.size() == 5 ? "YES" : "NO") << endl;

    return 0;
}