#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
int main()
{
	ll n,x,y,i;
	set<ll>s,s1;
	cin>>n;
	for(i=0;i<n;i++)
	{
		cin>>x>>y;
		s.insert(x);
		s1.insert(y);
	}
	if(s.size()==1 || s1.size()==1)
		cout<<"YES";
	else
		cout<<"NO";
}