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) throws IOException{
        new Solution().run();
    }
    
    public void run() throws IOException{
        Scanner in = new Scanner(System.in);
        BufferedWriter log = new BufferedWriter(new OutputStreamWriter(System.out));
        int n = in.nextInt();
        
        double tan = 0l, newTan =0l;
        boolean hline = true, vline=true;
        
        int x = in.nextInt();
        int y = in.nextInt();
        
        for(int i=1;i<n;i++){
            int z = in.nextInt();
            int t = in.nextInt();
            
            hline = (z==x)&&hline;
            vline = (t==y)&&vline;
            
        }
        
        log.write("" +((hline||vline)?"YES":"NO")+"\n"); 
        
        log.flush();
    }
}