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

Lemma countBLeafCT_mono_le: forall n1 n2 s, n1 <= n2 -> countBLeafCT n1 s <= countBLeafCT n2 s .