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 roller_coaster ( Speed VARCHAR, LENGTH VARCHAR )

### Question ###
What are the speeds of the longest roller coaster?

### Accurate SQL ###

SELECT Speed FROM roller_coaster ORDER BY LENGTH DESC LIMIT 1