r, g, b = map(int, input().split())

count = 0

while r > 0 or g > 0 or b > 0:
    if r == 0:
        if g > 2:
            r += 1
            g -= 2
        elif b > 2:
            r += 1
            b -= 2
        else:
            break
    if g == 0:
        if r > 2:
            g += 1
            r -= 2
        elif b > 2:
            g += 1
            b -= 2
        else:
            break
    if b == 0:
        if r > 2:
            b += 1
            r -= 2
        elif g > 2:
            b += 1
            g -= 2
        else:
            break

    r -= 1
    g -= 1
    b -= 1
    count += 1

print(count)