#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <deque>
#include <map>
#include <math.h>
#include <cmath>
#include <cstdio>
#include <cstring>

#define fr(n) for(i=0; i<n; i++)
#define INF (1<<30)
#define VI vector<int>
#define ll long long
#define LL unsigned long long

using namespace std;


int main() {
	
	ll t,n,m,g,l,y,q,i,j,p,s=0,k,x;
	cin>>n;
	bool b = true,bx = true;
	fr(n){
		cin>>x>>y;
		if(i==0){
			m = x;
			l = y;
		}else{
			if(x!=m){
				b = false;
			}
			if(y!=l){
				bx = false;
			}
		}
		if(!b && !bx){
			cout<<"NO";
			return 0;
		}
	}
	cout<<"YES";

	return 0;

}