#include <bits/stdc++.h>
using namespace std;

#define repu(i, begin, end) for (__typeof(begin) i = (begin) - ((begin) > (end)); i != (end) - ((begin) > (end)); i += 1 - 2 * ((begin) > (end)))
#define repe(i, begin, end) for (__typeof(begin) i = (begin); i != (end) + 1 - 2 * ((begin) > (end)); i += 1 - 2 * ((begin) > (end)))
#define mem(a, x) memset(a, x, sizeof(a))
#define all(a) a.begin(), a.end()
#define count_bits(x) __builtin_popcount(x)
#define count_bitsll(x) __builtin_popcountll(x)
#define least_bits(x) __builtin_ffs(x)
#define least_bitsll(x) __builtin_ffsll(x)
#define most_bits(x) 32 - __builtin_clz(x)
#define most_bitsll(x) 64 - __builtin_clz(x)

vector<string> split(const string &s, char c) {
	vector<string> v;
	stringstream ss(s);
	string x;
	while (getline(ss, x, c)) v.push_back(x);
	return v;
}

#define error(args...) { vector<string> _v = split(#args, ','); err(_v.begin(), args); }

void err(vector<string>::iterator it) {}

template<typename T, typename... Args>
void err(vector<string>::iterator it, T a, Args... args) {
	cerr << it -> substr((*it)[0] == ' ', it -> length()) << " = " << a << '\n';
	err(++it, args...);
}

typedef long long ll;
const int MOD = 1000000007;

template<class T> inline T tmin(T a, T b) {return (a < b) ? a : b;}
template<class T> inline T tmax(T a, T b) {return (a > b) ? a : b;}
template<class T> inline void amax(T &a, T b) {if (b > a) a = b;}
template<class T> inline void amin(T &a, T b) {if (b < a) a = b;}
template<class T> inline T tabs(T a) {return (a > 0) ? a : -a;}
template<class T> T gcd(T a, T b) {while (b != 0) {T c = a; a = b; b = c % b;} return a;}

const int N = 5;
int x[N], y[N];

const double EPS = 1e-10;
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));
    }
    P operator * (double d) {
        return P(x * d, y * d);
    }
    double dot(P p) {
        return add(x * p.x, y * p.y);
    }
    double det(P p) {
        return add(x * p.y, -y * p.x);
    }
};

bool comp_x(const P &p, const P &q) {
    if (p.x != q.x) return p.x < q.x;
    return p.y < q.y;
}

vector<P> convex_hull(P *ps, int n) {
    sort(ps, ps + n, comp_x);
    int k = 0;
    vector<P> qs(n + 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(int argc, char *argv[]) {
    ios_base::sync_with_stdio(false);

    P ps[N];
    repu(i, 0, N) cin >> ps[i].x >> ps[i].y;
    vector<P> qs = convex_hull(ps, N);
    printf("%s\n", qs.size() == N ? "YES" : "NO");
    
    return 0;
}