public static void main(String args[]){
        
          for (int i = 17; i < 42; i++) {
            if (i == 21) {
                i = 36;
            }
            
            for ( int j = 1; j <= 4; j++) {
                MassDownload md = new MassDownload();
                md.change(i,j);
                Thread download = new Thread(md);
                download.start();
                
            }
    }
    }