x, y, z = map(int, input().split())
if x > y:
    moto_ball = y
    amari = x-y
elif x== y:
    moto_ball = y
    amari = 0
else:
    moto_ball = x
    amari=y-x
if amari >= z:
    print(moto_ball+z)
else:#amari < z
    z_z = z+amari
    #print("moto_ball",moto_ball)
    #print(z_z)
    print(moto_ball+(z_z//2))