>>> from control import subtract_time

>>> subtract_time(3, 45, 2, 35)
(1, 10)
>>> subtract_time(2, 20, 2, 15)
(0, 5)
>>> subtract_time(3, 5, 1, 55)
(1, 10)
>>> subtract_time(5, 15, 2, 35)
(2, 40)