# coding: utf-8
def II(): return int(input())
def ILI(): return list(map(int, input().split()))


def read():
    R, G, B = ILI()
    return R, G, B


def solve(R, G, B):
    rgb = [R, G, B]
    rgb.sort()
    while rgb[2] - rgb[0] > 1:
        rgb[2] -= 2
        rgb[0] += 1
        rgb.sort()

    ans = rgb[0]
    return ans


def main():
    params = read()
    print(solve(*params))


if __name__ == "__main__":
    main()