import java.net.*;
import java.io.*;

public class Pulse {
	public static void main( String [] argv ) throws IOException {
		DatagramSocket s = new DatagramSocket( Integer.parseInt(argv[0]) );

		while ( true ) {
			DatagramPacket packet = new DatagramPacket(new byte [1024], 1024);
			s.receive( packet );
			String message = new String( packet.getData() );
			System.out.println( "Heartbeat from: " + 
						packet.getAddress().getHostName() + " - " + message );
		}
	}
}