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 prevX = 0, prevY = 0;
        int sameX = 1;
        int sameY = 1;
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            
            if(a0 != 0) {
                if(prevX != x)
                    sameX = 0;
                if(prevY != y)
                    sameY =0;
            }
            
            if(sameX==0 && sameY==0) {
                System.out.println("NO");
                return;
            }           
            
            prevX = x;
            prevY = y;
        }
        System.out.println("YES");
    }
}