hill = ((from company in db.Companies
where x.ID_comp > company.ID_comp
orderby company.ID_comp
select new { id = company.ID_comp.ToString() })
.Union((
    from company in db.Companies
    where x.ID_comp > company.ID_comp
    orderby company.ID_comp descending
    select new { id = company.ID_comp.ToString() })))
.Select(y => y.id)