Database: talkingdata
Question: Among the male users, how many users use device model of Desire 820?
SQL: SELECT COUNT(T1.device_id) FROM gender_age AS T1 INNER JOIN phone_brand_device_model2 AS T2 ON T1.device_id = T2.device_id WHERE T2.device_model = 'Desire 820' AND T1.gender = 'M'