:- set_prolog_flag(verbose,silent).
:- prompt(_, '').
:- use_module(library(readutil)).

main:-
	process,
	halt.

down(Y,X):-
    Y>=0,
    write(X),
    write(' = '),
    write(Y),
    nl,
    K is Y-1,
    down(K,X).

down(Y,_) :- Y < 0.

process:-
	down(5,'X'),
	true.

:- main.