import bisect
def findTime(timings, time):
	timings_int = bisect.bisect_left(timings, time)
	#print(timings_int)

	if timings_int == len(timings): return "-1"

	hh,mm = timings[timings_int].split(':')
	hh,mm = int(hh), int(mm)
	h,m = time.split(':')
	h, m = int(h), int(m)

	if (mm-m) < 0:
		m = m - mm
		mm = 60
		hh-=1

	return str(hh-h)+":"+str(mm-m)


if __name__ == '__main__':
	res = findTime(["04:03", "05:06","06:32"], "03:33")
	print(res)