Definition share_metric (n : nat) (s : canonTree) : nat :=
match n with
| 0 => 0
| S n => match le_dec (height s) n with
| left _ => countBLeafCT n s + 1
| right _ => 0
end
end.

(*L49*)
Lemma share_metric_err  : forall s n,
n <= height s ->
share_metric n s = 0.