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_17492 ( "Subjects" text, "First Year" text, "Second Year" text, "Third Year" text, "Fourth Year" text )

### Question ###
How many classes are taken in the third year when pag-unawa was taken in the first year?

### Accurate SQL ###

SELECT COUNT("Third Year") FROM table_17492 WHERE "First Year" = 'Pag-unawa'