def unify(hour, min, sec=0):
    return (hour * 60 + min) * 60 + sec


def time(km, sec_per_km):
    return km * sec_per_km


def add_zero(s):
    return '0' * (2 - len(s)) + s


def format(cur_time):
    hour = add_zero(str((cur_time // 60 // 60) % 24))
    min = add_zero(str((cur_time // 60) % 60))
    sec = add_zero(str(cur_time % 60))
    return hour + ':' + min + ':' + sec


start = unify(6, 52)
light = unify(0, 8, 15)
hard = unify(0, 7, 12)
print(format(start + time(1, light) + time(3, hard) + time(1, light)))