#!/usr/bin/perl

use warnings;
use strict;
use POSIX qw/ pow /;

sub convert_from_base26 {
   my ($total, $exp);
   my ($val) = @_;

   $total += (ord($_) - (ord('a') - 1)) * pow(26, $exp++)
      for split('', lc(reverse($val)));

   return $total;
}

print "Enter a value: ";
while (<>) {
   chomp;
   print convert_from_base26($_)."\n";
   print "Enter a value: ";
}