s,v = map(int,input().split()) if s%v == 0: t = int(s/v) + 10 else: t= int(s/v) + 1 + 10 if t <= 480: n = 480 - t if n%60<10: print('0{}:0{}'.format(n//60,n%60)) else: print('0{}:{}'.format(n//60,n%60)) else:
n = 24*60-(t -480) if n%60<10: print('0{}:0{}'.format(n//60,n%60)) else: print('{}:{}'.format(n//60,n%60))