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();
        
        String[] points = new String[n];
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            points[a0] = x+"|"+y;
        }
        if(n<2){
            System.out.println("YES");
            return;
        }
        String orientation = "H";
        if(points[0].substring(points[0].indexOf("|")+1).equals(points[1].substring(points[1].indexOf("|")+1))){
            orientation = "V";
        } else if(!points[0].substring(0,points[0].indexOf("|")).equals(
            points[1].substring(0, points[1].indexOf("|")))){
            System.out.println("NO");
            return;
        }
        if(orientation.equals("H")){
            for(int i = 0; i < n-1; i++){
                if(!points[i].substring(0,points[i].indexOf("|")).equals(
                    points[i+1].substring(0, points[i+1].indexOf("|")))){
                    System.out.println("NO");
                    return;
                }
            }
            System.out.println("YES");
            return;
        } else {
            // orientation = "V"
            for(int i = 0; i < n-1; i++){
                if(!points[i].substring(points[i].indexOf("|")+1).equals(
                    points[i+1].substring( points[i+1].indexOf("|")+1))){
                    System.out.println("NO");
                    return;
                }
            }
            System.out.println("YES");
            return;
        }
    }
}