Need help in SQL query - Urgent

I have a user database and i need help forming a query. Table = users fields = sign_in_count , last_sign_in_at

These are two queries which gives me following results :-

select *
from users
where last_sign_in_at >= '2015-08-01' and sign_in_count != ''

gives me 131000 rows.

select *
from users
where last_sign_in_at between '2015-05-01' and '2015-09-11' and
      sign_in_count <> ''

gives me 203000 rows.

so the difference of users in 72,000 users who have signed in at least once between 05/15 to 08/15.

I need to know the no of users from these 72k users who have logged in more than once.

via Chebli Mohamed