#!/usr/bin/perl -w
# taipoweracctchecksum -- 計算台灣電力公司之客戶電號之檢算號
# Compute Taiwan Power Company customer account number checksums
# Copyright       : http://www.fsf.org/copyleft/gpl.html
# Author          : 積丹尼 Dan Jacobson -- http://jidanni.org/comp/checksums/
# Created On      : Jan 2005
# Last Modified On: Sat Jan 15 00:56:41 2005
# Update Count    : 86
# 參考  Reference : https://wapp8.taipower.com.tw/naeb200e.asp
# 使用例子 Usage example: $ echo 1111111111 | taipoweracctchecksum
# 11111111115
use strict;
my $limit = 21;
while (<>) {
    chomp;
    die "$_: 請輸入未冠檢號之電號共十碼如 0000000000" unless /^(\d{2})\d{8}$/;
    die "$_: 前 \"$1\" 大於 $limit" if $1 > $limit;
    my ( $c, $f );
    for ( split '' ) { map $c += $_, split '', $_ * ( 1 + ( $f = !$f ) ) }
    printf "$_%d\n", $c % 10;
}