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 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