s,v=map(int,input().split())
t=s/v+10
h1=(480-t)//60
m1=(480-t)%60
h2=(t-480)//60
m2=(t-480)%60
if 0<=t<8*60:
        print("%.2d:%.2d"%(h1,m1))
elif 8*60<t<=24*60+8*60:
        print("%.2d:%.2d"%(h2,m2))