source(3).
edge(0,1).
edge(1,2).
edge(1,5).
edge(2,5).
edge(3,5).
edge(3,5).

%input :- [reachin1000].    % one way of reading input facts
%:- include(reachin1000).   % 2nd way of reading input facts

reach(X) :- source(X).
reach(Y) :- reach(X), edge(X,Y).

:- table reach/1.

printReach :- reach(X), write(X), write(' '), fail.
printReach.

%timeReach :- cputime(X), input, printReach, cputime(Y), T is Y-X, write(T).
%timeReach :- input, cputime(X), printReach, cputime(Y), T is Y-X, write(T).
timeReach :- cputime(X), printReach, cputime(Y), T is Y-X, write(T).