Fixpoint power (base : nat) (exp : nat) : nat :=
match exp with
| 0 => 1
| S n => base * (power base n)
end.

(*L43*)
Lemma countBLeafCT_mono_le: forall n1 n2 s,
n1 <= n2 ->
countBLeafCT n1 s <= countBLeafCT n2 s .