import java.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        int s[]=new int[n];
        int t[]=new int[n];
        int flag1=0;
       
        
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            s[a0]=x;
            t[a0]=y;
           
        }
         for(int a0 = 0; a0 < n-1; a0++)
         {
             
             if(s[a0]==s[a0+1]||t[a0]==t[a0+1])
             {
                 flag1=1;
                 
             }
            else if(s[a0]!=s[a0+1]||t[a0]!=t[a0+1])
            {
                flag1=0;
                 break;
                
                
            }
                
             /*if(t[a0]==t[a0+1])
             {
              flag2=1;   
             }*/
             
             
         }
        
        if(flag1==1)
        {
            System.out.println("YES");
            
        }
        else
       {
            System.out.println("NO");
            
        }
    }
}