emads3

# https://www.hackerrank.com/challenges/weather-observation-station-20/problem
# Example on Sakila DB
# select case
#            when count(actor_id) % 2 = 0 then (
#                select sum(actor_id)
#                from (
#                         select *
#                         from (
#                                  select actor_id
#                                  from actor a