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 a[] = new int[n];int b[] = new int[n];
        int ans = 0;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            a[a0] = x;
            b[a0] = y;
        }
        int tx = a[0];
        int ty = b[0];
        boolean h = true,v=true;
        for(int a0 = 1; a0 < n; a0++){
            if(a[a0] == tx ){
                h=true;
                //System.out.println("1a0 = " + a[a0] + " b0 = " + b[a0] + " b =  " +(b[a0-1]+1)  );
            } else if(b[a0] == ty ){
                v=true;
                //System.out.println("2a0 = " + b[a0] + " b0 = " + a[a0] + " b =  " +(a[a0-1]+1)  );
            } else{
                h=false;
                v=false;
                break;
            }
            
        }
        if(h==true||v==true){
            System.out.println("YES");
        }else{
            System.out.println("NO");
        }
    }
}