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();
        HashMap<Integer,Integer> hm=new HashMap<Integer,Integer>();
        HashMap<Integer,Integer> hm2=new HashMap<Integer,Integer>();
        
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            if(hm.containsKey(x))
                {
                int cc=hm.get(x);
                hm.put(x,cc+1);
            }
            else
                {
                hm.put(x,1);
            }
             if(hm2.containsKey(y))
                {
                int cc=hm2.get(y);
                hm2.put(y,cc+1);
            }
            else
                {
                hm2.put(y,1);
            }
        }
        boolean ans=false;
        for(int m:hm.keySet())
            {
            int cc=hm.get(m);
            if(cc==n)
                {
                ans=true;
            }
        }
         for(int m:hm2.keySet())
            {
            int cc=hm2.get(m);
            if(cc==n)
                {
                ans=true;
            }
        }
        if(ans)
            {
            System.out.println("YES");
        }
        else
            {
            System.out.println("NO");
            
        }
    }
}