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_18 ( frequency__per_hour_ VARCHAR, line VARCHAR, destination VARCHAR )

### Question ###
How many frequencies have a line of East London and destination of Crystal Palace?

### Accurate SQL ###

SELECT COUNT(frequency__per_hour_) FROM table_name_18 WHERE line = "east london" AND destination = "crystal palace"