sub amount {
    my $num = shift;
    return ''    if $num < 0;
    return '0K'  if $num == 0;
    return '<1K' if $num < 1024;

    my @suffix = qw/K M G T P/;
    my $offset = -1;

    while( $num >= 1024 and $offset < scalar @suffix ) {
        ++$offset;
        $num = int( $num / 1024 );
    }
    return "$num$suffix[$offset]";
}