translation.en: Neither can attack the other, because to attack the other side you've got to come down the mountain into the valley and then up the other side, and you're completely exposed.
translation.zh: 谁都无法攻击到对方，因为如果要攻击对方 就得先从山脊下到山谷里来 然后再上到对方那里去，这样就完全暴露了自己