begin real A;
   begin real A;
      begin real A;
         begin real A;
            begin real A;
               begin real A;
                  begin real A;
                     begin real A;
                        begin real A;
                           begin real A;
                              begin real A;
                                 begin real A;
                                    begin real A;
                                       begin real A;
                                          begin real A;
                                          end
                                       end
                                    end
                                 end
                              end
                           end
                        end
                     end
                  end
               end
            end
         end
      end
   end
end