#include<bits/stdc++.h>
#define MX 100000
#define pb push_back
#define mp make_pair
#define fs first
#define sec second
#define sc scanf
#define pr printf
using namespace std;
int main(){
	int n,m,i,j,k;
	cin>>n;
	int a[n][2];
	for(i=0;i<n;++i)
		cin>>a[i][0]>>a[i][1];
	int flag=0;
	  if(a[1][0]==a[0][0]){
	  	for(i=2;i<n;++i)
	  	{
	  		if(a[i][0]!=a[0][0])
	  		{
	  			flag=1;
	  			break;
	  		}
	  	}
	  }
	  else if(a[1][1]==a[0][1]){
	  	for(i=2;i<n;++i)
	  	{
	  		if(a[i][1]!=a[0][1])
	  		{
	  			flag=1;
	  			break;
	  		}
	  	}
	  }
	  else
	  	flag=1;
	  if(flag==0)
	  	cout<<"YES";
	  else
	  	cout<<"NO";
	return 0;
}