import java.io.*;
import java.net.*;
public class OOPServer {
   public static void main(String [ ] args) throws IOException{
      ServerSocket ss = new ServerSocket ( 2445);
      while ( true ){
          Socket s = ss.accept( );
          DataInputStream dis = new DataInputStream ( s.getInputStream( ));
          DataOutputStream dos = new DataOutputStream ( s.getOutputStream( ));
          int query = dis.readInt( );
          dos.writeInt(query * 2);
          dis.close( );
          dos.close( );
      }
    }
 }