public static long?GetClimbersGroup(this ONLCompetition comp, int birthyear, bool genderFemale)
        {
            int age        = comp.GetCompYear() - birthyear;
            var groupsList = (from cl in comp.ONLGroupsCompLinks
                              where cl.ONLGroup.genderFemale == genderFemale &&
                              cl.ONLGroup.oldYear >= age &&
                              cl.ONLGroup.youngYear <= age
                              select cl.iid).ToArray();

            if (groupsList.Length < 1)
            {
                return(null);
            }
            else
            {
                return(new long?(groupsList[0]));
            }
        }