#include <bits/stdc++.h>
#define rep(i, a) for (int i = 0; i < (a); i++)
#define rep2(i, a, b) for (int i = (a); i < (b); i++)
#define repr(i, a) for (int i = (a) - 1; i >= 0; i--)
#define repr2(i, a, b) for (int i = (b) - 1; i >= (a); i--)
using namespace std;
typedef long long ll;
const ll inf = 1e9;
const ll mod = 1e9 + 7;

typedef ll D;
typedef complex<D> P;
const D eps = 0;

D dot(P a, P b) {
    return real(conj(a) * b);
}

D cross(P a, P b) {
    return imag(conj(a) * b);
}

bool comp(P a, P b) {
    if (a.real() != b.real()) return a.real() < b.real();
    return a.imag() < b.imag();
}

vector<P> convex_full(vector<P> &ps) {
    int n = ps.size();
    sort(ps.begin(), ps.end(), comp);
    int k = 0;
    vector<P> qs(n * 2);
    for (int i = 0; i < n; i++) {
        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() {
    vector<P> ps;
    rep (i, 5) {
        D x, y;
        cin >> x >> y;
        ps.emplace_back(x, y);
    }

    vector<P> cf = convex_full(ps);

    if (cf.size() == 5) {
        cout << "YES" << endl;
    } else {
        cout << "NO" << endl;
    }
}