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();
        boolean verticalCheck=true;
        boolean horizontalCheck=true;
        int x = in.nextInt();
        int y = in.nextInt();
        int a=x;
        int b=y;
        for(int a0 = 1; a0 < n; a0++){
            if(verticalCheck || horizontalCheck){                
             x = in.nextInt();
             y = in.nextInt();
                if (x!=a){
                   verticalCheck=false; 
                }else if(y!=b){
                    horizontalCheck=false;
                }
                a=x;
                b=y;
            }else{
                System.out.println("NO");
                break;
            }
            
        }
        if (verticalCheck || horizontalCheck){
            System.out.println("YES");
        }
        
    }
}