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 x = in.nextInt();
        int y = in.nextInt();
     
        int countx=1;
        int county=1;
        int a=0,b=0;
        for(int a0 = 0; a0 < n-1; a0++){
            
        	a = in.nextInt();
            b = in.nextInt();
         
            if(a==x){
            	countx++;
            }
            
            if(b==y){
            	county++;
            }
        }
        
        
        if(countx==n || county==n){
        	System.out.println("YES");
        }else
        	System.out.println("NO");
    }
}