:- set_prolog_flag(verbose,silent). :- prompt(_, ''). :- use_module(library(readutil)). main:- process, halt. process:- read_line_to_codes(current_input, Codes), ( Codes = end_of_file -> true ; ( Codes \= [], number_codes(Int, Codes) -> (Int is 42 -> true ; writeln(Int), process ) ; true ) ). :- main.