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 pre_x= in.nextInt();
        int pre_y=in.nextInt();
        
        int x_cnt=0;
        int y_cnt=0;
        
        for(int a0 = 1; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            
            if(x!=pre_x){
               x_cnt++; 
            }
            if(y!=pre_y){
                y_cnt++;
            }
            
            pre_x=x;
            pre_y=y;
        }
        
        if(x_cnt >0 && y_cnt>0){
            System.out.println("NO");
        }
        else{
            System.out.println("YES");
        }
    }
}