input_list = list(map(int,input().split()))
x = input_list[0]
y = input_list[1]
z = input_list[2]

res = 0

def min(a, b):
    if a >= b:
        return b
    else:
        return a

# 青と赤の差を白で埋める
delta = x - y
change = min(abs(delta), z)

if delta > 0:
    y += change
    z -= change
elif delta < 0:
    x += change
    z -= change
    
res += x
# 残った白で紫を作る
res += int(z / 2)

print(res)