Input TRS:
    1: a__zeros() -> cons(0(),zeros())
    2: a__U11(tt(),L) -> a__U12(tt(),L)
    3: a__U12(tt(),L) -> s(a__length(mark(L)))
    4: a__length(nil()) -> 0()
    5: a__length(cons(N,L)) -> a__U11(tt(),L)
    6: mark(zeros()) -> a__zeros()
    7: mark(U11(X1,X2)) -> a__U11(mark(X1),X2)
    8: mark(U12(X1,X2)) -> a__U12(mark(X1),X2)
    9: mark(length(X)) -> a__length(mark(X))
    10: mark(cons(X1,X2)) -> cons(mark(X1),X2)
    11: mark(0()) -> 0()
    12: mark(tt()) -> tt()
    13: mark(s(X)) -> s(mark(X))
    14: mark(nil()) -> nil()
    15: a__zeros() -> zeros()
    16: a__U11(X1,X2) -> U11(X1,X2)
    17: a__U12(X1,X2) -> U12(X1,X2)
    18: a__length(X) -> length(X)
Number of Rules: 18
Direct QWPOS(mPol) ... failed.