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 []xArr = new int[n];
        int [] yArr = new int[n];
        for(int a0 = 0; a0 < n; a0++){
            xArr[a0] = in.nextInt();
            yArr[a0] = in.nextInt();
        }
        
        int initX = xArr[0];
        int initY = yArr[0];
        
        int pointer = 1;
        boolean done = false;
        
        while(pointer < xArr.length){
            if(xArr[pointer] == initX){
                pointer++;
            }else{
                pointer = 1;
                break;
            }
        }
        if(pointer == xArr.length)
            done = true;
        if(!done){
          while(pointer < xArr.length){
              if(yArr[pointer] == initY)
                  pointer++;
              else
                  break;
          }
            
          if(pointer == yArr.length)
             done = true;
        }
        
        if(done)
            System.out.println("YES");
        else
            System.out.println("NO");
    }
}