sub v{
    ord($_[0])-ord("A")+1
}

##</code><code>##

sub v {
    my (@letters) = split //, $_[0];
    my $sum = 0;
    my $pwr = 1;
    while ( @letters ) {
        my $digit = ord( pop( @letters )) - ord("A") + 1;
        $sum += $digit * $pwr;
        $pwr *= 26;
    }
    return $sum;
}

print v("AB"),"\n";