human
Considering the provided database schema and associated query, produce SQL code to retrieve the answer to the query. 
###Database Schema: Year, Class, Team, Points, Wins
###Question: How many points numbers had a class of 250cc, a year prior to 1978, Yamaha as a team, and where wins was more than 0?
gpt
SELECT COUNT Points FROM table WHERE Class = 250cc AND Year < 1978 AND Team = yamaha AND Wins > 0