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 s = new Scanner(System.in);
        int no=s.nextInt();
        int i=0;
        int x=s.nextInt();
        int y=s.nextInt();
        for(i=0;i<no-1;i++)
        {
            int xx=s.nextInt();
            int yy=s.nextInt();
            if(xx==x || yy==y)
            {
                x=xx;
            y=yy;
            continue;  
             
            }
            else
            {
            break;    
            }
            
               
        }
        if(i==no-1)
        {
            System.out.println("YES");
        }
        else
            {
             System.out.println("NO");
        }
        
        }
}