Let $h$ be the maximum possible number of levels of red-green tower, that can be built out of $r$ red and $g$ green blocks meeting the rules above.

令 $h$ 表示用 $r$ 个红积木和 $g$ 个绿积木所能搭建的塔的最大层数。

要不然样例 $2$ 就会看着很迷。