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 firstX = -1;
        int firstY = -1;
        int secondX = -1;
        int secondY = -1;
        boolean horizLine = false;
        boolean error = false;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if (firstX == -1) {
                firstX = x;
                firstY = y;
            }
            else if (secondX == -1) {
                secondX = x;
                secondY = y;
                if (secondX == firstX && secondY != firstY) {
                    horizLine = true;
                }
                else {
                    horizLine = false;
                }
            }
            else {
               if (horizLine) {
                   if (firstX != x) {
                       System.out.println("NO");
                       error = true;
                       break;
                   }
               }
               else if (firstY != y) {
                   System.out.println("NO");
                   error = true;
                   break;
               }
            }
        }
        
        if (!error) {
            System.out.println("YES");
        }
    }
}