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 sc = new Scanner(System.in);
	int n=sc.nextInt();
       int x=sc.nextInt();
	int y=sc.nextInt();
		int a,b,f1=0,f2=0;
	for(int i=1;i<n;i++)
	{
	a=sc.nextInt();
	b=sc.nextInt();
	if(a!=x)
	{ 
	f1=1;	
	}
        if(b!=y)
            f2=1;
        }
if(f1==0 || f2 ==0)
System.out.println("YES");
else 
System.out.println("NO");
				
    }
}