#include <iostream>

using namespace std;


int main (){
    
    int n;
    cin>>n;
    
    int x,y,x1,y1;
    cin>>x>>y;
    x1=x;
    y1=y;
    
    int i=1;
    int ind_x=0, ind_y=0;
    
    do {
        
        cin>>x>>y;
        
        if(!ind_x)
        {if(x!=x1)
            ind_x=1;}
        else if(!ind_y)
        {if (y!=y1)
            ind_y=1;}
        
        if(ind_x && ind_y)
        {cout<<"NO";
         return 0;}
        i++;
        
        
    }while (i<n);
    
    cout<<"YES";
        
    
    
}