#!/usr/bin/env -S csi -script

(import (chicken file posix) (chicken io) (chicken string))

(define the-lines
    (read-lines (open-input-file* (file-open "input" (+ open/rdonly)))))

(define (score-of-char c)
    (define alpha "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ")
    (define (go i)
        (if (substring=? c alpha 0 i 1)
            (+ i 1)
            (go (+ i 1))))
    (go 0))

(define (find-common-char line)
    (define halves (string-chop line (/ (string-length line) 2)))
    (define a (car halves))
    (define b (cadr halves))
    (define (go i j)
        (if (substring=? a b i j 1)
            (substring a i (+ i 1))
            (if (< j (string-length b))
                (go i (+ j 1))
                (go (+ i 1) 0))))
    (score-of-char (go 0 0)))

(define (sum ns) (foldl + 0 ns))

(print (sum (map find-common-char the-lines)))

(define (find-common-char-3 group)
    (define a (car group))
    (define b (cadr group))
    (define c (caddr group))
    (define (go i j k)
        (define (next-non-k)
            (if (< j (string-length b))
                (go i (+ j 1) 0)
                (go (+ i 1) 0 0)))
        (if (substring=? a b i j 1)
            (if (substring=? a c i k 1)
                (substring a i (+ i 1))
                (if (< k (string-length c))
                    (go i j (+ k 1))
                    (next-non-k)))
            (next-non-k)))
    (score-of-char (go 0 0 0)))

(print (sum (map find-common-char-3 (chop the-lines 3))))