{ pkgs ? import <nixpkgs> {} }: pkgs.mkShell {
  nativeBuildInputs = with pkgs; [
    sbcl
  ];
}

(defun process (instream) 
	(loop for line = (read-line instream nil) while line sum
				(calibration line)
	)
)
(defun calibration (line)
	(let ((a NIL) (b NIL))
		(loop for c across line do (let ((x (digit-char-p c)))
			(when x (setq b x) (unless a (setq a x)))
		))
		(when (and a b) (+ (* 10 a) b))
	)
)
(loop for arg in (cdr *posix-argv*) do 
	 (with-open-file (s arg :direction :input) (format T "~d~&" (process s)))
	)