(VAR IL L M N X X1 X2 X3 X4 )
(RULES 
        a__zeros -> cons(0, zeros)
        a__U11(tt, L) -> a__U12(tt, L)
        a__U12(tt, L) -> s(a__length(mark(L)))
        a__U21(tt, IL, M, N) -> a__U22(tt, IL, M, N)
        a__U22(tt, IL, M, N) -> a__U23(tt, IL, M, N)
        a__U23(tt, IL, M, N) -> cons(mark(N), take(M, IL))
        a__length(nil) -> 0
        a__length(cons(N, L)) -> a__U11(tt, L)
        a__take(0, IL) -> nil
        a__take(s(M), cons(N, IL)) -> a__U21(tt, IL, M, N)
        mark(zeros) -> a__zeros
        mark(U11(X1, X2)) -> a__U11(mark(X1), X2)
        mark(U12(X1, X2)) -> a__U12(mark(X1), X2)
        mark(length(X)) -> a__length(mark(X))
        mark(U21(X1, X2, X3, X4)) -> a__U21(mark(X1), X2, X3, X4)
        mark(U22(X1, X2, X3, X4)) -> a__U22(mark(X1), X2, X3, X4)
        mark(U23(X1, X2, X3, X4)) -> a__U23(mark(X1), X2, X3, X4)
        mark(take(X1, X2)) -> a__take(mark(X1), mark(X2))
        mark(cons(X1, X2)) -> cons(mark(X1), X2)
        mark(0) -> 0
        mark(tt) -> tt
        mark(s(X)) -> s(mark(X))
        mark(nil) -> nil
        a__zeros -> zeros
        a__U11(X1, X2) -> U11(X1, X2)
        a__U12(X1, X2) -> U12(X1, X2)
        a__length(X) -> length(X)
        a__U21(X1, X2, X3, X4) -> U21(X1, X2, X3, X4)
        a__U22(X1, X2, X3, X4) -> U22(X1, X2, X3, X4)
        a__U23(X1, X2, X3, X4) -> U23(X1, X2, X3, X4)
        a__take(X1, X2) -> take(X1, X2)
        
)