Below is the list of tables from the database along with their columns and datatype. Need to generate an accurate SQL query for the question.
Only use the columns present in the respective table. Only use the columns which are required to generate the SQL query. Only use table joins if required and not otherwise.

### Tables ###
TABLE: CREATE TABLE table_25695027_1 ( valves VARCHAR, years_built VARCHAR )

### Question ###
How many types of valves were used on this engine that was built on 1902-05?

### Accurate SQL ###

SELECT COUNT(valves) FROM table_25695027_1 WHERE years_built = "1902-05"