'''
按照题意，图中必然存在欧拉回路，把所有路长度加起来，除以铲雪
速度即可
'''

import sys
import math

s = sys.stdin.readline()
total_len = 0
speed = 20000 / 60
while True:
    try:
        s = sys.stdin.readline()
    except:
        break

    if s == '':
        break

    a1, b1, a2, b2 = map(int, s.split())
    total_len += math.sqrt((a2-a1)**2 + (b2-b1)**2)

min_val = int(total_len*2 / speed + 0.5)
h, m = min_val // 60, min_val % 60
print('{:d}:{:02d}'.format(h, m))