package ru.skuznetsov;

public class Calculate{

  public static void main(String[] args){

    System.out.println("Hello world");
  }

}

package ru.skuznetsov;

public class Calculate{
/**
*  Hello world
* @param args    
*/
  public static void main(String[] args){

    System.out.println("Hello world");
  }

}

update with comments