#!/usr/bin/env python3
from collections import namedtuple
Timestamp = namedtuple('Timestamp', ['h', 'm', 's'])
Timestamp.__str__ = lambda self: "{h:02}:{m:02}:{s:02}".format(
h=self.h, m=self.m, s=self.s
)
def get_timestamp(s):
slices = (
(0, 2), (3, 5), (6, 9),
)
return Timestamp(*(int(s[l:r]) for l, r in slices))
SECS_IN_MINUTE = 60
SECS_IN_HOUR = SECS_IN_MINUTE * 60
SECS_IN_DAY = SECS_IN_HOUR * 24
def get_seconds(t):
ret = t.h * SECS_IN_HOUR
ret += t.m * SECS_IN_MINUTE
ret += t.s
return ret
Timestamp.__int__ = get_seconds
def get_timestamp_from_seconds(secs):
h = secs // SECS_IN_HOUR
h %= 24
secs %= SECS_IN_HOUR
m = secs // SECS_IN_MINUTE
secs %= SECS_IN_MINUTE
s = secs
return Timestamp(h, m, s)
A, B, C = [int(get_timestamp(input())) for _ in range(3)]
tm2 = 2*B + (C-A) % SECS_IN_DAY
tm = tm2 // 2 + tm2 % 2
tm = get_timestamp_from_seconds(tm)
print(tm)
