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.
from sys import stdin; inp = stdin.readline
from math import dist, ceil, floor, sqrt, log
from collections import defaultdict, Counter
def IA(): return list(map(int, inp().split()))
def FA(): return list(map(float, inp().split()))
def SA(): return inp().split()
def I(): return int(inp())
def F(): return float(inp())
def S(): return input()
def O(l:list): return ' '.join(map(str, l))

def main():
    ch, cm = map(int, S().split(':'))
    dh, dm = map(int, S().split(':'))
    mins = cm-dm
    carry = 0 
    if mins < 0: 
        mins += 60 
        carry = 1
    if carry:
        ch -= carry 
    if ch < 0:
        ch = 23
    if ch-dh < 0:
        ch = 24-dh 
    else:
        ch-=dh 
    ch = str(ch)
    if len(ch)==1:
        ch = '0'+ch 
    mins = str(mins)
    if len(mins)==1:
        mins = '0'+mins
    return ch + ':' + mins
        


if __name__ == '__main__':
    print(main())