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