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 main():
    def f(sh, sm, th, tm):
        sh -= th
        sm -= tm
        if sm < 0:
            sh -= 1
            sm %= 60
        if sh < 0:
            sh %= 24
        return (sh, sm)
    s = map(int, input().split(':'))
    t = map(int, input().split(':'))
    return "{:02d}:{:02d}".format(*f(*s, *t))
print(main())
