s,v = map(int,input().split())
t = s/v+10
h = t //60
f = t % 60
if f != 0:
    h = int(h +1)
else :
    h = int (h)
if t >= 24*60:
    print('0')
elif h > 8:
    h = 32 -h
    if f <= int (f):
        f= int(f)
    else:
        f= int(f+1)
    if h == 24:
        print('00:%d'%(60-f))
    else:
        print("%d:%d"%(h,(60-f)))
else:
    h = 8-h
    print('0%d:%d'%(h,60-f))

#3#5WA了 tips：代码有点乱因为是想到什么写什么勿怪勿怪、 不知道测试点信息、请问是哪个地方出纰漏了、 已经自己改了四遍看的脑壳痛、救救孩子叭?