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 x1 = 100, y1 = 100;
        boolean bx = true, by = true;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(x1 != x && x1 != 100)
                bx = false;
            if(y1 != y && y1 != 100)
                by = false;
            x1 = x;
            y1 = y;
        }
        if (bx || by) {
            System.out.println("YES");
        }
        else 
            System.out.println("NO");
        
    }
}