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 prex=in.nextInt();
        int prey=in.nextInt();
        boolean flag=false;
        for(int a0 = 0; a0 < n-1; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(prex!=x && prey!=y){
                flag=true;
                break;
            }
        }
        if(flag==true)
            System.out.println("NO");
            else
                System.out.println("YES");
        }
    }