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 counter=0;
           int[] p=new int[n];
        int[] q=new int[n];
        for(int a0 = 0; a0 < n; a0++){
            p[a0] = in.nextInt();
            q[a0] = in.nextInt();
                
        }
        int j=0,k=0;
        for (int i=1;i<n;i++){
            if(p[i-1]==p[i]){
                j++;
            }
            else if(q[i-1]==q[i]){
                k++;
            }
        }
        if((counter==n)||(j==n-1)||(k==n-1)){
            System.out.println("YES");
        }
        else{
            System.out.println("NO");
        }
    }
}