#include<iostream>
using namespace std;
int main()
{
	int n,count =0,count1=0;
	cin>>n;
	int arr[n], arr1[n];
	for(int i=0;i<n;i++)
	{
	
	cin>>arr[i]>>arr1[i];
}
	
	for(int i=0;i<n;i++)
	{
		
		if(arr[i]==arr[0])
		{
			count++;
		}
		
		else if (arr1[i]==arr1[0])
		{
			count1++;
			
		}
		}
	
		
		if(count==n || count1 == n)
		cout<<"YES";
	
		
		else
		cout<<"NO";
}