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.
import sys, io, os
import math
import bisect
import heapq
import string
from collections import defaultdict,Counter,deque
input = sys.stdin.readline
 
def I():
    return input()
 
def II():
    return int(input())
 
def MII():
    return map(int, input().split())
 
def LI():
    return list(input().split())
 
def LII():
    return list(map(int, input().split()))
 
def GMI():
    return map(lambda x: int(x) - 1, input().split())
 
def LGMI():
    return list(map(lambda x: int(x) - 1, input().split()))
 
def WRITE(out):
  return print('\n'.join(map(str, out)))
 
def WS(out):
  return print(' '.join(map(str, out)))
 
def WNS(out):
  return print(''.join(map(str, out)))

'''
convert minutes; if overflow add to hours mod 60
convert hours; if overflow mod 24
'''

def solve():
  sh, sm = I().split(':')
  th, tm = I().split(':')
  sh = int(sh)
  sm = int(sm)
  th = int(th)
  tm = int(tm)

  if sh < th or (sh == th and sm < tm):
    sh += 24
  
  if sm < tm:
    sm += 60
    sh -= 1
  
  ph = sh - th
  pm = sm - tm

  print("{:02d}".format(ph) +':'+ "{:02d}".format(pm))

solve()