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