Question 77
Let a positive integer $n$ be given. The cube of size $2n + 1$ consists of $(2n + 1)^3$ unit cubes. Each cube is colored either green or orange. It is known that among any 8 unit cubes that form a $2 \times 2 \times 2$ cube, there are at most 4 green cubes. Find the maximum number of green cubes.