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 hor = true;
        int x0 = 0, y0 = 0; 
        String res = "YES";
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if (a0 == 0) {
                x0 = x;
                y0 = y;
           } else if (a0 == 1) {
                if (x0 == x) {
                    hor = true;
                } else if (y0 == y) {
                    hor = false;
                } else  {
                    res = "NO";
                    break;
                }
            } else {
                if (hor) {
                    if (x0 != x) {
                        res = "NO";
                        break;
                    }
                } else {
                    if (y0 != y) {
                        res = "NO";
                        break;
                    }
                }
            }
        }
        System.out.println(res);
    }
}