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);
        Map<Integer,Integer> m=new HashMap<Integer,Integer>();
        Set<Integer> s=new HashSet<Integer>();
        int n = in.nextInt();
        String result="";
        for(int a0 = 0; a0 < n; a0++){
            int x = in.nextInt();
            int y = in.nextInt();
            m.put(x,y);
        }
        if(m.size()==1)
            result="YES";
        else
            {
        for(Map.Entry<Integer,Integer> e:m.entrySet())
            {
            s.add(e.getValue());
            
        }
            if(s.size()==1)
                result="YES";
            else
                result="NO";
        }
        System.out.print(result);
    }
}