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.
'''
Created on Jun 4, 2014

@author: Nathaniel
'''
end = input().split(':')
start = input().split(':')
startmin = int(start[0])
endmin = int(end[0])
startsec = int(start[1])
endsec = int(end[1])

secdiff = endsec-startsec
mindiff = endmin-startmin
if secdiff<0:
    secdiff+=60
    mindiff-=1
if mindiff<0:
    mindiff+=24

print (('0' if mindiff < 10 else '') + str(mindiff) +':'+ ('0' if secdiff<10 else '') + str(secdiff))
