$ a :- write(1), b, !, write(2).
 $ b.
 $ b :- c.
 $ c.

 $ a1 :- write(1), b1, !, write(2).
 $ a1 :- write(3).
 $ b1.
 $ b1 :- c.
 $ c1.

 $ a2 :- b2, write(1), c2, fail.
 $ b2 :- !.
 $ b2 :- write(oh).
 $ c2.

 $ a3 :- repeat, write(1), c3, fail.
 $ c3 :- !.
 $ c3 :- write(oh).

 $ a4 :- repeat, write(1), c4, fail.
 $ c4.
 $ c4 :- write(oh).

 $ a5 :- repeat, write(1), c5, !, fail.
 $ c5 :- write(ah).
 $ c5 :- write(oh).

 $ a6 :- repeat, b6, write(1), c6, fail.
 $ b6 :- !.
 $ b6 :- write(oh).
 $ c6.

 $ alph :- repeat, bet, write(o), fail .
 $ bet :- !.

 $ ato1 :- repeat, abo1, fail .
 $ abo1 :- a1conc(X,Y,[a,b,c]),a1conc(X,Y,[a,b,c]),
           a1conc(X,Y,[a,b,c]),!, _read(U).
 $ a1conc(X,Y,Z) :-  conc(X,Y,Z), write(X).

 $ a7 :- b7, eq(X,c7), call(X), !.
 $ b7.
 $ c7 :- write(1).
 $ c7 :- write(2).

 $ a8 :- b8, eq(X,c8), call(X).
 $ b8.
 $ c8 :- write(1), !.
 $ c8 :- write(2).

 $ a10 :- b10, eq(X,c10), call(X).
 $ b10.
 $ c10 :- write(1).
 $ c10 :- write(2).

 $ a11 :- repeat, eq(X,c11), call(X), fail.
 $ c11 :- write(1), !.
 $ c11 :- write(2).