How many labels of the restaurant have an unknown country?
unknown county refers to county = 'unknown'
SELECT COUNT(T1.label) FROM generalinfo AS T1 INNER JOIN geographic AS T2 ON T1.city = T2.city WHERE T2.county = 'unknown'
database name:db_id restaurant
geographic table geographic Cols: city dtype text, country dtype text, region dtype text, 
generalinfo table generalinfo Cols: id restaurant dtype integer, label dtype text, food type dtype text, city dtype text, review dtype real, 
location table location Cols: id restaurant dtype integer, street number dtype integer, street name dtype text, city dtype text, 
