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 arr[]=new int[2*n];
        int count1=0;
        int count2=0;
        int i=0;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            
            if(i-2<0|| arr[i-2]==x)
              {  arr[i]=x;
            i++;
            }
            else{
                count1++;
                i++;
            }
        if(i-2<0||arr[i-2]==y)
            {
            arr[i]=y;
            i++;
        }
        else
            {
           count2++;
            i++;
        }
            
           
        }
        if(count1==0||count2==0)
            {
            System.out.println("YES");
        }
        else
            System.out.println("NO");
    }
}