rgb = list(map(int, raw_input().split()))

num = 0
while True:
	mxi = max(rgb)
	mni = min(rgb)
	if mxi - mni <= 1:
		num = mni
		break
	for i in range( len(rgb) ):
		if mxi == rgb[i]:
			mx = i
		if mni == rgb[i]:
			mn = i
	rgb[mx] -= 2
	rgb[mn] += 1

print min(rgb)