s,v=map(int,input().strip().split()) t=float((s/v)+10) if t<=860: a=int(7-(t//60)) b=int(60-(t%60)) else: a=int(23-((t-(860))//60)) b=int(60-((t-(8*60))%60)) h=f'{a:02d}' min=f'{b:02d}' print(h+":"+min)