How to count the number of rows being grouped in group by?

Let’s say I have a table with columns as email, topic_id. One email can corresponds to one topic_id multiple times. I want to apply group by based on email and topic_id. But I’m unble to count how many rows are grouped together.
Example.

email           topic_id     
abc@gmail.com     1
abc@gmail.com     1 
abc@gmail.com     1
abc@gmail.com     2
xyz@gmail.com     1
xyz@gmail.com     1
xyz@gmail.com     1

The output should give :

    email        topic_id    count   
abc@gmail.com     1            3
abc@gmail.com     2            1
xyz@gmail.com     1            3

>Solution :

simple group by and count? :

select email,topic_id, count(*) 
from tablename
group by email,topic_id