#include <iostream>
using namespace std;
int main (){
int n;
static int b[20][2];
cin >>n;
int a;
for (int i = 0; i < n; ++i)
{
	if (b[i][0]>=-10&&b[i][1]>=-10&& b[i][0]<=10&& b[i][1]<=10)
	{
		cin >>b[i][0]>>b[i][1];
	}

}
int flag=0;
int temp;
temp=b[0][0];
for (int i = 1; i < n; ++i)
{
	if (temp!=b[i][0])
	{
		//cout <<"NO";
		flag=0;
		break;
		
	}
	else {flag=1;
		
		}

}

temp=b[0][1];
if (flag==0)
{
	for (int i = 1; i < n; ++i)
	{
		if (temp==b[i][1])
	{
		flag=1;
		
	}
	else {
		//cout <<"NO";
		break;
	}
	}
}
//else cout<<"YES";
if (flag==0)
{
	cout <<"NO";

}
else cout <<"YES";



	return 0;
}