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 px=in.nextInt();
        int py=in.nextInt();
        boolean bx=true,by=true;
        for(int a0 = 1; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            
            if(bx && x==px){
                
            }else{
                bx=false;
            }
            
            if(by && y==py){
                
            }else{
                by=false;
            }
            
            if(bx || by){
                
            }else{
                System.out.println("NO");
                return;
            }
            
        }
        
        System.out.println("YES");
    }
}