Input TRS:
    1: sel(s(X),cons(Y)) -> sel(X,Z)
    2: f(X) -> cons(X)
    3: g(|0|()) -> s(|0|())
    4: g(s(X)) -> s(s(g(X)))
    5: sel(|0|(),cons(X)) -> X
Extra variable in rule 1.
NO