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.
t1 = input()
t2 = input()

h1 = int(t1[0:2])
h2 = int(t2[0:2])
m1 = int(t1[3:5])
m2 = int(t2[3:5])

n = (h1-h2 if h2-h1 < 0 else 24 - (h2-h1) % 24) - (1 if (m1-m2) < 0 else 0)
u = (0 if (m1 - m2 > 0) else 60) + m1 - m2

print(str(n).zfill(2) + ":" + str(u).zfill(2))
   				 	   	 		    				  			 	