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[] x = new int[n];
        int[] y = new int[n];
        int flag1=0,flag2=0,flag3=0;
        for(int i = 0;i < n; i++){
            x[i]=in.nextInt();
            y[i]=in.nextInt();
          
        }
        
        for(int i=1;i<n;i++)
            {
                if(x[i]!=x[0])
                    {
                        flag1=1;
                }
        }
         for(int i=1;i<n;i++)
            {
                if(y[i]!=y[0])
                    {
                        flag2=1;
                }
        }
        for(int i=0;i<n;i++)
            {
                if(x[i]!=y[i])
                    {
                        flag3=1;
                }
        }
        if(flag1==0)
            System.out.println("YES");
        else if(flag2==0)
            System.out.println("YES");
             else if(flag3==0)
            System.out.println("YES");
            
        else
            System.out.println("NO");
        
        
    }
}