class Clock(object):
    def __init__(self, time):
        while True:
            try:
                self.hour = int(time[0:2])
                self.minute = int(time[3:])
                while not (23 >= self.hour >= 0 and 59 >= self.minute >= 0 and len(time) == 5):
                    print "Invalid time."
                    time = raw_input("Please reenter the time: ")
                    self.hour = int(time[0:2])
                    self.minute = int(time[3:])
                break
            except:
                print "I need numbers, not that garbage."
                time = raw_input("Please reenter the time: ")
    def tick(self):
        self.minute += 1
        if self.minute % 60 == 0:
            self.minute = 0
            self.hour += 1
            if self.hour == 24:
                self.hour = 0
        self.report()
    def report(self):
        hour = ("00" + str(self.hour))[-2:]
        minute = ("00" + str(self.minute))[-2:]
        print hour + ":" + minute