#include <bits/stdc++.h>

using namespace std;

void fast_io() {
	ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
}

int main() {
	fast_io();
	int n;
	cin >> n;
	vector<string> s(n), t(n);
	for (int i = 0; i < n; i++) {
		cin >> s[i] >> t[i];
	}
	for (int i = 0; i < n; i++) {
		bool s_ok = true, t_ok = true;
		for (int j = 0; j < n; j++) {
			if (i == j) continue;
			if (s[i] == s[j] || s[i] == t[j]) s_ok = false;
			if (t[i] == t[j] || t[i] == s[j]) t_ok = false;

			if (!s_ok && !t_ok) {
				cout << "No" << endl;
				return 0;
			}
		}
	}
	cout << "Yes" << endl;
}