#include <iostream>
#include <algorithm>
using namespace std;

int main() {
	int n;
	cin >> n;
	string a[n][2];

	for(int i = 0; i < n; i++) cin>> a[i][0] >> a[i][1];

	

	bool t1_flg = false;
	bool t2_flg = false;
	
	for(int b = 0; b < n ; b++){
		string t1 = a[b][0];
		string t2 = a[b][1];
		for(int i = b + 1 ; i < n ; i++)
		{
			if(t1 == a[i][0] || t1 == a[i][1])
			{
				t1_flg = true;
			}
			if(t2 == a[i][0] || t2 == a[i][1])
			{
				t2_flg = true;
			}
		}
		if (t1_flg && t2_flg) break;
	}
	
	
	if (t1_flg && t2_flg)
	{
		cout << "No" << endl;
	}
	else
	{
		cout << "Yes" << endl;
	}

}