Instance CompSpecs : compspecs. make_compspecs prog. Defined.
Definition Vprog : varspecs. mk_varspecs prog. Defined.
Definition putchars_spec := DECLARE _putchars putchars_spec.
Definition getchars_spec := DECLARE _getchars getchars_spec.

Lemma div_10_dec : forall n, 0 < n ->
(Z.to_nat (n / 10) < Z.to_nat n)%nat.