r = map(int,raw_input().split())
r.sort()
while r[0] + 3 <= r[2]:
	s = r[2] - r[0]
	if s % 2 == 1:s -= 1
	r[2] = r[2] - s
	r[0] = r[0] + (s / 2)
	r.sort()
print min(r)