#include<bits/stdc++.h>

using namespace std;
typedef long long ll;
typedef double db;
const int N = 1000 + 5;
#define int long long
const int mod = 1000000000;

struct point {
    int x, y;

    point operator+(const point &a) const {
        return {x + a.x, y + a.y};
    }

    point operator-(const point &a) const {
        return {x - a.x, y - a.y};
    }
};

int det(point &a, point &b) {
    return a.x * b.y - a.y * b.x;
}

void solve() {
    int n;
    cin >> n;
    vector<point> a(n + 3);
    for (int i = 0; i < n; i++) cin >> a[i].x >> a[i].y;
    a[n] = a[0];
    a[n + 1] = a[1];
    a[n + 2] = a[2];
    int jud = 0;
    int ans = 1;
    for (int i = 0; i < n; i++) {
        point tmp1 = (a[i + 1] - a[i]);
        point tmp2 = (a[i + 2] - a[i]);
        int tt = det(tmp1, tmp2);
        if (jud == 0) {
            if (tt > 0) {
                jud = 1;
            } else if (tt < 0) {
                jud = -1;
            } else {
                ans = 0;
            }
        } else {
            if (tt == 0 || (tt < 0 && jud == 1) || (tt > 0 && jud == -1)) ans = 0;
        }
    }
    jud = 0;
    point f = a[1] - a[0];
    for (int i = 2; i < n; i++) {
        point tmp = (a[i] - a[0]);
        int tt = det(f, tmp);
        if (jud == 0) {
            if (tt > 0) {
                jud = 1;
            } else if (tt < 0) {
                jud = -1;
            } else {
                ans = 0;
            }
        } else {
            if (tt == 0 || (tt < 0 && jud == 1) || (tt > 0 && jud == -1)) ans = 0;
        }
        f = tmp;
    }
    jud = 0;
    f = a[1] - a[0];
    for (int i = 2; i < n; i++) {
        point tmp = (a[i] - a[0]);
        int tt = det(f, tmp);
        if (jud == 0) {
            if (tt > 0) {
                jud = 1;
            } else if (tt < 0) {
                jud = -1;
            } else {
                ans = 0;
            }
        } else {
            if (tt == 0 || (tt < 0 && jud == 1) || (tt > 0 && jud == -1)) ans = 0;
        }
    }
    if (ans) {
        cout << "Yes\n";
    } else {
        cout << "No\n";
    }

}

signed main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout.tie(nullptr);
    int T = 1;
//    cin >> T;
    while (T--) solve();
    return 0;
}