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) {
     HashSet<Integer> h1 = new HashSet<Integer>();
		HashSet<Integer> h2 = new HashSet<Integer>();
		 
	        Scanner in = new Scanner(System.in);
	        int n = in.nextInt();
	        for(int a0 = 0; a0 < n; a0++){
	            int x = in.nextInt();
	            int y = in.nextInt();
	            h1.add(x);
	            h2.add(y);
	        }
	       if(h1.size() ==1 || h2.size() ==1){
	    	   System.out.println("YES");
	       }
	       else
	    	   System.out.println("NO");
    }
}