First and Last Call on the Same Day

# Write your MySQL query statement below
with temp as (
select caller_id as c_id, recipient_id as r_id, call_time from calls c1 
union all
select recipient_id as c_id, caller_id as r_id, call_time from calls c2
    ), 
    temp2 as (
select *, 
first_value(r_id) over(partition by c_id, date(call_time) order by date(call_time)) as f_v, last_value(r_id) over(partition by c_id, date(call_time) order by date(call_time))  as l_v  from temp order by date(call_time)
    )
    
select distinct c_id as 'user_id' from temp2 where f_v=l_v