public OnClientPreConnect(const String:name[], const String:pass[], const String:ip[], const String:authid[])
{
    if (GetClientCount(false) < MaxClients)
    {
        return;
    }

    new AdminId:admin = FindAdminByIdentity(AUTHMETHOD_STEAM, authid);

    if (admin == INVALID_ADMIN_ID)
    {
        return;
    }

    if (GetAdminFlag(admin, Admin_Reservation))
    {
        new target = SelectKickClient();

        if (target)
        {
            KickClientEx(target, "Slot reserved");
        }
    }
}