"""
Read file into texts and calls.
It's ok if you don't understand how to read files.
"""
import csv

with open('texts.csv', 'r') as f:
    reader = csv.reader(f)
    texts = list(reader)

with open('calls.csv', 'r') as f:
    reader = csv.reader(f)
    calls = list(reader)

"""
TASK 4:
The telephone company want to identify numbers that might be doing
telephone marketing. Create a set of possible telemarketers:
these are numbers that make outgoing calls but never send texts,
receive texts or receive incoming calls.

Print a message:
"These numbers could be telemarketers: "
<list of numbers>
The list of numbers should be print out one per line in lexicographic order with no duplicates.
"""

telemarkList=[]
textSend,textRec,textTime=zip(*texts)
callSend,callRec,callTime,callDur=zip(*calls)

for caller in callSend:
    if caller not in (textSend+textRec+callRec):
        telemarkList.append(caller)

callerSet=sorted(set(telemarkList))

print('These numbers could be telemarketers:\n{}'.format('\n'.join(callerSet)))
