Among the countries that use Bosnian as their language, how many of them don't have a positive population growth rate?
SELECT COUNT(DISTINCT T1.Name) FROM country AS T1 INNER JOIN language AS T2 ON T1.Code = T2.Country INNER JOIN population AS T3 ON T3.Country = T2.Country WHERE T2.Name = 'Bosnian' AND T3.Population_Growth < 0