George woke up and saw the current time *s* on the digital clock. Besides, George knows that he has slept for time *t*. 

Help George! Write a program that will, given time *s* and *t*, determine the time *p* when George went to bed. Note that George could have gone to bed yesterday relatively to the current time (see the second test sample).
The first line contains current time *s* as a string in the format "hh:mm". The second line contains time *t* in the format "hh:mm" — the duration of George's sleep. It is guaranteed that the input contains the correct time in the 24-hour format, that is, 00 ≤ *hh* ≤ 23, 00 ≤ *mm* ≤ 59.
# http://codeforces.com/contest/387/problem/A

wake = input().strip().split(":")
time = input().strip().split(":")
wake[0], wake[1] = int(wake[0]), int(wake[1])
time[0], time[1] = int(time[0]), int(time[1])

sleep = [-1, -1]
if(wake[1] >= time[1]):
    sleep[1] = wake[1]-time[1]
    if(wake[0] >= time[0]):
        sleep[0] = wake[0]-time[0]
    else:
        sleep[0] = 24 - (time[0] - wake[0])
else:
    sleep[1] = 60 - (time[1] - wake[1])
    if(wake[0] >= time[0] + 1):
        sleep[0] = wake[0]-time[0]
    else:
        sleep[0] = 24 - (time[0] + 1 - wake[0])

print('{0:02}'.format(sleep[0])+":"+'{0:02}'.format(sleep[1]) )
