while True:
	d,s1,s2=[int(e) for e in raw_input().split()]
	if d==0 and s1==0 and s2==0:
		break

	s1,s2=min(s1,s2),max(s1,s2)
	val=d*(s2-s1)

	h=val/(s1*s2)
	val%=(s1*s2)
	val*=60

	m=val/(s1*s2)
	val%=(s1*s2)
	val*=60

	s=val/(s1*s2)

	if 2*(val%(s1*s2))>=(s1*s2):
		s+=1

	print "%d:"%h+":".join(("%d"%e).zfill(2) for e in [m,s])