L1=list(map(int,input().split(":")))
L2=list(map(int,input().split(":")))
T1 = L1[0]*3600+L1[1]*60+L1[2]
T2 = L2[0]*3600+L2[1]*60+L2[2]
T = T2-T1
if T<0:
T+=24*60*60
if T==0:
print("24:00:00")
else:
print("%02d:%02d:%02d"%(T//(60*60),(T%(60*60))//60,T%60))