def check(x):
    need = 0
    rest = 0
    for i in range(3):
        if (color[i] >= x):
            rest += (color[i] - x) / 2
        else:
            need += x - color[i]
    if (rest >= need):
        return True
    else:
        return False


color = map(int, raw_input().split())

right = 1145141919810
left = 0

while (right - left > 1):
    med = (right + left) / 2
    if (check(med)):
        left = med
    else:
        right = med
print left