ingre = map(int, raw_input().split())

ans = 0

while True:
    make = min(ingre)
    ans += make
    ingre = [i - make for i in ingre]    
    if min(ingre)==0:
        if sum(ingre) <3: break
        else: 
            ingre[ingre.index(max(ingre))] -= 2
            ingre[ingre.index(0)] += 1

print ans