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_name_28 (year VARCHAR, competition VARCHAR, event VARCHAR)

### Question ###
How many years was the 400 m event in the olympic games?

### Accurate SQL ###

SELECT COUNT(year) FROM table_name_28 WHERE competition = "olympic games" AND event = "400 m"