text: a = [*map(int, input().split(':'))]
  b = [*map(int, input().split(':'))]
  s = a[0]*3600 + a[1]*60 + a[2]
  e = b[0]*3600 + b[1]*60 + b[2]
  if s > e:
      e += 3600*24
  r = e - s
  print("{0:02d}".format(r//3600), end=':')
  r %= 3600
  print("{0:02d}".format(r//60), end=':')
  r %= 60
  print("{0:02d}".format(r))
  