Among the current legislators who have accounts on both http://thomas.gov, how many of them have accounts on instagram?
have accounts on both http://thomas.gov refers to thomas_id is NOT null; have accounts on instagram refers to instagram is not null;
SELECT COUNT(DISTINCT T1.bioguide_id) FROM current AS T1 INNER JOIN `social-media` AS T2 ON T1.bioguide_id = T2.bioguide WHERE T1.thomas_id IS NOT NULL AND T2.instagram IS NOT NULL