;;; https://gitlab.com/Syndamia/senzill
(require :senzill)
(use-package :senzill.collections)

;;; After loading this file, if you enter a blank line, code will work on each
;;; line of input, until "end" is typed.
;;; Otherwise, the input is taken as a filename and code will be executed
;;; over each line in the file until EOF.

(defvar *prog-input*)
(let ((ui (read-line)))
  (if (equal ui "")
    (setq *prog-input* *standard-input*)
    (setq *prog-input* (open ui))))

(defconstant +process-characters+ 4)

(let
  ((inpt (read-line *prog-input* NIL)) (met '()) (sop -1))

  (loop until (or (string= inpt "end") (not inpt)) do
        (loop for i from 0 to (- (length inpt) 1)
              until (> sop 0) do

              (loop until (not (find (char inpt i) met)) do
                    (pop-back met))
              (push (char inpt i) met)
              (if (= (length met) +process-characters+)
                (setq sop (+ 1 i))))

        (setq inpt (read-line *prog-input* NIL)))

  (print sop))

(if (not (eq *prog-input* *standard-input*))
  (close *prog-input*))