with cte as(
select *,
case 
    when t.x=t.y and  (SELECT COUNT(*) FROM functions AS temp WHERE temp.x = t.y AND temp.y = t.x) > 1 then 'true'
    when t.x<t.y and (select count(*) from functions as temp where temp.x=t.y and temp.y=t.x)>0 then 'true'
    else ''
    end as flag
from functions as t
group by x,y 

)
select x,y
from cte
where flag='true'
order by x