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 a[]=new int[n];
        int b[]=new int[n];
        for(int i = 0; i < n; i++){
            a[i]=in.nextInt();
            b[i]=in.nextInt();
        }
        int counta=1;
        int countb=1;
        for(int i=0;i<n-1;i++)
            {
            if(a[i]==a[i+1])
                counta++;
            if(b[i]==b[i+1])
                countb++;
        }
        if(counta==n || countb==n)
            System.out.println("YES");
        else
            System.out.println("NO");
    }
}