from math import ceil
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: 
            maximum = max(ingre)
            transfer = int(ceil(maximum/6.0))
            ingre[ingre.index(maximum)] -= transfer*2
            ingre[ingre.index(0)] = transfer

print ans