#include <bits/stdc++.h>

using namespace std;
int static const N = 100100;
int n , x[N] , y[N];

int main() {
	scanf("%i",&n);
	int xx , yy;
	xx = yy = -100;
	for(int i=0;i<n;i++)
	{
		int q , w;
		cin>>q>>w;
		if(q != xx && xx != -200)
		{
			if(xx != -100)
				xx = -200;
			else
				xx = q;
		}
		if(w != yy && yy != -200)
		{
			if(yy != -100)
				yy = -200;
			else
				yy = w;
		}
	}
	if(!(xx == -200 && yy == -200))
		printf("YES\n");
	else
		printf("NO\n");
	
	return 0;
}