for_calista.py

import datetime

STARTHOUR, STARTMINUTE = map(int, input("Enter Shift Start Time (HH:MM): ").split(':'))
BREAKSTARTHOUR, BREAKSTARTMINUTE = map(int, input("Enter Break Start Time (HH:MM): ").split(':'))
BREAKENDHOUR, BREAKENDMINUTE = map(int, input("Enter Break End Time (HH:MM): ").split(':'))
ENDHOUR, ENDMINUTE = map(int, input("Enter Shift End Time (HH:MM): ").split(':'))

START_TIME = datetime.time(STARTHOUR, STARTMINUTE)
BREAKSTART_TIME = datetime.time(BREAKSTARTHOUR, BREAKSTARTMINUTE)
BREAKEND_TIME = datetime.time(BREAKENDHOUR, BREAKENDMINUTE)
END_TIME = datetime.time(ENDHOUR, ENDMINUTE)

FULL_SHIFT = datetime.timedelta(hours=END_TIME.hour, minutes=END_TIME.minute) - datetime.timedelta(hours=START_TIME.hour, minutes=START_TIME.minute)
BREAK = datetime.timedelta(hours=BREAKEND_TIME.hour, minutes=BREAKEND_TIME.minute) - datetime.timedelta(hours=BREAKSTART_TIME.hour, minutes=BREAKSTART_TIME.minute)
CHARGEABLE = FULL_SHIFT - BREAK

print("Shift time: {0}".format(FULL_SHIFT))
print("Break time: {0}".format(BREAK))
print("Chargeable time: {0}".format(CHARGEABLE))