How many times did other regions make positive sales in DS platform?
other regions refers to region_name = 'Other'; positive sales refers to num_sales > 0; DS platform refers to platform_name = 'DS';
SELECT COUNT(DISTINCT T2.id) FROM platform AS T1 INNER JOIN game_platform AS T2 ON T1.id = T2.platform_id INNER JOIN region_sales AS T3 ON T1.id = T3.game_platform_id INNER JOIN region AS T4 ON T3.region_id = T4.id WHERE T1.platform_name = 'DS' AND T4.region_name = 'Other' AND T3.num_sales > 0