sub wdhms {
    my( $weeks, $days, $hours, $minutes, $seconds, $sign, $res ) = qw/0 0 0 0 0/;

    $seconds = shift;
    $sign    = $seconds == abs $seconds ? '' : '-';
    $seconds = abs $seconds;

    ($seconds, $minutes) = ($seconds % 60, int($seconds / 60)) if $seconds;
    ($minutes, $hours  ) = ($minutes % 60, int($minutes / 60)) if $minutes;
    ($hours,   $days   ) = ($hours   % 24, int($hours   / 24)) if $hours;
    ($days,    $weeks  ) = ($days    %  7, int($days    /  7)) if $days;

    $res = sprintf '%ds',     $seconds;
    $res = sprintf "%dm$res", $minutes if $minutes or $hours or $days or $weeks;
    $res = sprintf "%dh$res", $hours   if             $hours or $days or $weeks;
    $res = sprintf "%dd$res", $days    if                       $days or $weeks;
    $res = sprintf "%dw$res", $weeks   if                                $weeks;

    return "$sign$res";
}