Database: financial
Question: Among the account opened, how many female customers who were born before 1950 and stayed in Sokolov?
SQL: SELECT COUNT(T2.client_id) FROM district AS T1 INNER JOIN client AS T2 ON T1.district_id = T2.district_id WHERE T2.gender = 'F' AND STRFTIME('%Y', T2.birth_date) < '1950' AND T1.A2 = 'Sokolov'