sub encode {
    my ($text, @alphabet) = @_;
    local $" = '';
    eval "\$text =~ tr/a-zA-Z/\L@alphabet\U@alphabet\E/";
    $text
}

sub decode {
    my ($text, @alphabet) = @_;
    local $" = '';
    eval "\$text =~ tr/\L@alphabet\U@alphabet\E/a-zA-Z/";
    $text
}