from collections import Counter
import sys

sys.setrecursionlimit(10 ** 6)
int1 = lambda x: int(x) - 1
p2D = lambda x: print(*x, sep="\n")
def MI(): return map(int, sys.stdin.readline().split())
def MF(): return map(float, sys.stdin.readline().split())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LF(): return list(map(float, sys.stdin.readline().split()))
def LLI(rows_number): return [LI() for _ in range(rows_number)]

def main():
    def ok(m):
        over=0
        for a in aa:
            if a>=m:
                over+=(a-m)//2
            else:
                over+=a-m
        if over>=0:return True
        return False

    aa=LI()
    l=-1
    r=sum(aa)//3+1
    while l+1<r:
        m=(l+r)//2
        if ok(m):l=m
        else:r=m
    print(l)

main()