#include <iostream>
#include <vector>
#include <utility>
#include <cmath>

using namespace std;

int main(void)
{
	int n;
	cin >> n;
	vector<pair<int, int> > A(n);
	for (int i = 0; i < n; i++)
	{
		cin >> A[i].first >> A[i].second;
	}
	pair<int, int> count;
	count.first = 1;
	count.second = 1;
	for (int i = 1; i < n; i++)
	{
		if (A[i].first == A[i - 1].first)
			count.first++;
		if (A[i].second == A[i - 1].second)
			count.second++;
	}
	if (count.first == n || count.second == n)
		cout << "YES" << endl;
	else
		cout << "NO" << endl;
	return 0;
}