S = map(int,raw_input().split())
S.sort()
if (S[1]-S[0])*2 <= S[2]-S[1]:
	print S[1] + (S[2]-(S[1]-S[0])*2-S[1])/5
else:
	t = (S[2]-S[1])/2*2
	ans = S[0] + t/2
	print ans + (0 if S[2]-t-ans < 3 else (S[1]-ans)/2)