#include <bits/stdc++.h>
#define ull unsigned long long int
using namespace std;
int main() 
{
	int T,x2,y2,x1,y1,flag;
	double initslope,slope;
	cin>>T;
	cin>>x1>>y1;
	cin>>x2>>y2;
	if(x1==x2)
		flag=0;
	else if(y1==y2)
		flag=1;
	else
	{
		cout<<"NO"<<endl;
		return 0;
	}
	if(flag==0)
	{
		for (int i = 0; i < T-2; i += 1)
		{
			cin>>x2>>y2;
			if(x1!=x2)
			{
				cout<<"NO"<<endl;
				return 0;
			}
		}
	}
	else
	{
		for (int i = 0; i < T-2; i += 1)
		{
			cin>>x2>>y2;
			if(y1!=y2)
			{
				cout<<"NO"<<endl;
				return 0;
			}
		}
	}
	cout<<"YES"<<endl;
	return 0;
}