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.
def ui(a):
    a = str(a)
    return '0'*(2-len(a))+a
a,b = map(int,input().split(':'))
c,d = map(int,input().split(':'))
t1 = 60*a+b
t2 = 60*c+d
if t1>=t2:
    dt = t1-t2
else:
    dt = 1440-t2+t1
print(ui(dt//60),':',ui(dt%60),sep='')