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 horizontal = false;
        int xprev=-1, yprev=-1;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if (a0 == 0) {
                xprev = x;
                yprev = y;
            }
            else if (a0 == 1) {
                if (xprev == x && yprev == y)
                    continue;
                else if (xprev == x)
                    horizontal = true;
                else if (yprev == y)
                    horizontal = false;
                else {
                    System.out.println("NO");
                    System.exit(0);
                }    
            }
            else {
                if (horizontal) {
                    if (xprev != x) {
                        System.out.println("NO");
                        System.exit(0);
                    }
                }
                else {
                    if (yprev != y) {
                        System.out.println("NO");
                        System.exit(0);
                    }
                }
            }
        }
        System.out.println("YES");
    }
}