#include<iostream>
#include<vector>
#include<string>
#include<fstream>
#include<algorithm>
#define forn(i,x,y) for(i = (x) ; i <= (y) ; ++i)
#define forr(i,x,y) for(i = (y) ; i >= (x) ; --i)
using namespace std;
int main()
{
	long long int flag=1,x,y,i,j,ans,n,xt,yt,xt2,yt2;
	cin >> n;
	cin >> xt >> yt;
	n--;
	do
	{
		cin >> xt2 >> yt2;
		n--;
	}while(xt==xt2 && yt==yt2 && n>0);
	
	if(xt==xt2)
		while(n>0)
		{
			n--;
			cin >> x >> y;
			if(x!=xt)
				flag=-1;
		}
	else if(yt==yt2)
		while(n>0)
		{
			n--;
			cin >> x >> y;
			if(y!=yt)
				flag=-1;
		}
	else 
		flag=-1;
	if(flag==-1)
		cout <<"NO\n";
	else
		cout <<"YES\n";
	return 0;
}