#include<bits/stdc++.h>
#define nl '\n'
#define pb push_back
#define MAX 100000
#define M 1000000007
typedef long long ll;
using namespace std;
int main()
{
	ios::sync_with_stdio(0);cin.tie(0);
	int i,j,n,x,y,xx,yy,fl1=0,fl2=0;
	cin>>n;
	cin>>x>>y;
	for(i=1;i<n;i++)
	{
		cin>>xx>>yy;
		if(xx!=x){
			fl1=1;
		}
		if(yy!=y){
			fl2=1;
		}
	}
	if(fl1==0 || fl2==0)
		cout<<"YES\n";
	else cout<<"NO\n";
	return 0;
}