Input TRS:
    1: zeros() -> cons(0(),n__zeros())
    2: U11(tt(),L) -> U12(tt(),activate(L))
    3: U12(tt(),L) -> s(length(activate(L)))
    4: length(nil()) -> 0()
    5: length(cons(N,L)) -> U11(tt(),activate(L))
    6: zeros() -> n__zeros()
    7: activate(n__zeros()) -> zeros()
    8: activate(X) -> X
Number of Rules: 8
Direct POLO(Sum) ... failed.