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

(*L44*)
Lemma countBLeafCT_mono_diff: forall n1 n2 s1 s2,
n1 <= n2 ->
(s1 <= s2)%ba ->
countBLeafCT n1 s2 - countBLeafCT n1 s1 <= countBLeafCT n2 s2 - countBLeafCT n2 s1.