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 [] arrx=new int[n];
		int [] arry=new int[n];
		
		for (int a0 = 0; a0 < n; a0++) {
			int x = in.nextInt();
			arrx[a0]=x;
			int y = in.nextInt();
			arry[a0]=y;
		}
		 
		 boolean alleq=true;
		 for (int i=1;i<arrx.length;i++)
		 {
			 if (arrx[i-1]!=arrx[i])
				 alleq=false;
		 }
		if (alleq==true)
			System.out.println("YES");
		else
			System.out.println("NO");
				
		 
		

	}

}