#include<iostream>
#include<math.h>
#include<algorithm>
#define ul unsigned long long
#define ll long long
using namespace std;
/*Authorised by Ravishankar Chaubey*/
int main(void)
{
	int n;
	cin>>n;
	int x[n],y[n],i;
	int fx=0,fy=0;
	for(i=0;i<n;++i)
	{
		cin>>x[i]>>y[i];
	}
	for(i=0;i<n-1;++i)
	{
		if(x[i]!=x[i+1])
			fx=1;
		if(y[i]!=y[i+1])
			fy=1;
	}
	if(fx==0||fy==0)
		cout<<"YES"<<endl;
	else
		cout<<"NO"<<endl;
	return 0;
}