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:- module skip.

:- interface.

:- import_module io.

:- pred main(io::di, io::uo) is det.

:- implementation.

:- import_module int.

main(!IO) :-
    a(1, X),
    a(2, Y),
    a(3, Z),
    write_int(X+Y+Z, !IO),
    nl(!IO).

:- pred a(int::in, int::out) is det.

a(Y, X) :- b(Y, A), c(A, B), d(B, X).

:- pred b(int::in, int::out) is det.

b(X, X+69).

:- pred c(int::in, int::out) is det.

c(A, B) :- e(A, C), f(C, B).

:- pred d(int::in, int::out) is det.

d(X, X).

:- pred e(int::in, int::out) is det.

e(X, X).

:- pred f(int::in, int::out) is det.

f(X, X).