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.
# Description of the problem can be found at http://codeforces.com/problemset/problem/387/A

l_s = list(map(int, input().split(":")))
l_t = list(map(int, input().split(":")))

if l_t[1] > l_s[1]:
    l_s[0] -= 1
    
print("%02d:%02d" % ((l_s[0] - l_t[0]) % 24, (l_s[1] - l_t[1]) % 60))