#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using vec = complex<ll>;
ll C(vec p, vec q) {
	return imag(conj(p) * q);
}
int main() {
	cin.tie(0)->sync_with_stdio(0);
	int n;
	cin >> n;
	vector<vec> a(n);
	for (vec &v : a) {
		ll x, y;
		cin >> x >> y;
		v = {x, y};
	}
	if (C(a[1] - a[0], a[2] - a[0]) < 0) reverse(a.begin(), a.end());
	for (int i = 0; i < n; i++) {
		if (C(a[(i + 1) % n] - a[i], a[(i + 2) % n] - a[i]) <= 0) {
			cout << "No" << "\n";
			return 0;
		}
	}
	cout << "Yes" << "\n";
	return 0;
}