rgb = list(map(int,input().split()))

l = 0
r = 10 ** 8

for i in range(100):
    rgb.sort()
    m = (l + r) // 2

    add = 0
    need = 0

    for j in range(3):
        if rgb[j] >= m:
            add += (rgb[j] - m) // 2
        else:
            need += (m - rgb[j])

    if need <= add:
        l = m
    else:
        r = m

print(m)