#include<bits/stdc++.h>

using namespace std;
int main(){
	int x,n,y;
	cin>>n;
	int flagx = 1,flagy =1;
	int arr[n][2];
	for(int i = 0;i< n;i++){
	  cin>>arr[i][0]>>arr[i][1];
	  //x = arr[i][0];
	  //y = arr[i][0];
	  
	}
	x = arr[0][0];
	y = arr[0][1];
	for(int i = 1;i< n;i++){
	  //cin>>intarr[i][0]>>arr[i][0];
	  if(arr[i][0] != x )flagx =0;
	  if(arr[i][1] != y)flagy = 0;
	  if(flagx ==0 && flagy == 0){
	   cout<<"NO"<<endl;
	  break;
}
        x = arr[i][0];
        y = arr[i][1];
}
if((flagx == 1 && flagy == 0 )||(flagx == 0 && flagy == 1))
cout<<"YES"<<endl;
return 0;
}