from math import ceil
s,v= map(int,input().split(' '))
t=ceil(s/v)
zong=t+10
su = 480 - zong
if zong == 480:
    print("00:00")
if su>0:
    shi = int(su/60)
    print(f"0{shi}:",end = "")
    if su - shi*60>=10:
        print( su - shi*60)
    else:
        print(f"0{su-shi*60}")
else:
    shi = -su
    x= 24- ceil(shi/60)
    if x>=10:
        print(f"{x}:",end = "")
    else:
        print(f"0{x}",end = '')
    f=60 - (shi - int(shi/60))
    if f>=10:
        print(f)
    else:
        print(f"0{f}")