get_string(String) :-
  current_input(Input),
  read_string(Input, ' \n', '', _, String).
 
get_number(Number) :-
  get_string(String),
  number_string(Number, String).

main :-
  get_string(S),
  string_chars(S,L),
  L = [H1,H|_],
  (H='B' -> writeln('ARC');writeln('ABC')).