#include <iostream>
#include <vector>
#include <cmath>
#include <memory>
#include <algorithm>
#include <set>
#include <map>
#include <queue>
#include <iomanip>
#include <bitset>
#include <string>
#include <list>
#include <deque>
#include <stack>
#include <limits>
#include <numeric>
#include <unordered_map>
#include <unordered_set>
#include <chrono>
#include <random>

using namespace std;
using ll = long long;
using ull = unsigned long long;
template <class T>
using max_heap = priority_queue<T>;
template <class T>
using min_heap = priority_queue<T, vector<T>, greater<>>;
ll ll_min = numeric_limits<ll>::min();
ll ll_max = numeric_limits<ll>::max();
ll ALPHABET_N = 26;
static const ll INF = ll_max / 10;
#define rep(i, n) for (ll i = (ll)0; i < (ll)n; i++)
#define rep_(i, k, n) for (ll i = (ll)k; i < (ll)n; i++)
#define all(a) a.begin(), a.end()

int main()
{
	ll n;
	cin >> n;
	vector<string> S(n), T(n);
	rep(i, n) cin >> S[i] >> T[i];
	map<string, ll> cnt;
	rep(i, n)
	{
		cnt[S[i]]++;
		cnt[T[i]]++;
	}
	bool ok = true;
	rep(i, n)
	{
		if (!(cnt[S[i]] == 1 || cnt[T[i]] == 1))
		{
			ok = false;
			break;
		}
	}
	cout << (ok ? "Yes" : "No") << endl;
	return 0;
}