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 lastx=20;
        int lasty=20;
        boolean inited = false;
        int quadVal = 0; // 0 for one point, 1 for vertical, 2 for horizontal
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if (! inited) {
                lastx = x;
                lasty = y;
                inited = true;
                quadVal = 0;
            } else {
                if (quadVal == 0) {
                    if (lastx == x) {
                        quadVal = 1;
                        continue;
                    } else if (lasty == y) {
                        quadVal = 2;
                        continue;
                    } else {
                        quadVal = -1;
                        break;
                    }
                } else if (quadVal == 1) {
                    if (lastx != x) {
                        quadVal = -1;
                        break;
                    }
                } else if (quadVal == 2) {
                    if (lasty != y) {
                        quadVal = -1;
                        break;
                    }
                } else {
                    //shouldn't be here
                    quadVal = -1;
                    break;
                }
            }
        }
        if (quadVal != -1) 
            System.out.println("YES");
        else
            System.out.println("NO");
    }
}