#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, s, t) for (ll i = s; i < (ll)(t); i++)
#define all(x) begin(x), end(x)

template <class T> bool chmin(T& x, T y) {
	return x > y ? (x = y, true) : false;
}
template <class T> bool chmax(T& x, T y) {
	return x < y ? (x = y, true) : false;
}

struct io_setup {
	io_setup() {
		ios::sync_with_stdio(false);
		std::cin.tie(nullptr);
		cout << fixed << setprecision(15);
	}
} io_setup;

void solve() {
	int n;
	cin >> n;
	vector<string> s(n), t(n);
	rep(i, 0, n) cin >> s[i] >> t[i];
	rep(i, 0, n) {
		int flg = 0;
		rep(j, 0, n) {
			if (j == i) continue;
			if (s[i] == s[j] || s[i] == t[j]) flg |= 1;
			if (t[i] == s[j] || t[i] == t[j]) flg |= 2;
		}
		if (flg == 3) {
			cout << "No\n";
			return;
		}
	}
	cout << "Yes\n";
}

int main() {
	int t = 1;
	// cin >> t;
	while (t--) solve();
}