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];
        x[0] = in.nextInt();
        y[0] = in.nextInt();
        int flagx=0,flagy=0;
 
             x[1] = in.nextInt();
             y[1] = in.nextInt();
            if(x[1]==x[0] || y[1]==y[0])
                {
                if(x[0]==x[1])
                    flagx=1;
                else
                    flagy=1;
            }
              int i;  
             for(i=2;i<n;i++)
                 {
                 //System.out.println(i);
                 x[i] = in.nextInt();
                 y[i] = in.nextInt();
                 if(flagx==1)
                     {
                      if(x[i]!=x[0]){
                     System.out.println("NO");
                          break; }
                    
                 }
                   else if(flagy==1)
                     {
                      if(y[i]!=y[0]) {
                     System.out.println("NO");
                    
                          break; }
                 }
                 
             }
       // System.out.println(flagx+" "+flagy+" "+i);
        
        if(flagx==0 && flagy==0) {
            System.out.println("NO");
        }
         else if(i==n)
             System.out.println("YES");
        
    }
}