The 4th day night. Hakuin-zenji said thare are 6 steps for Susokukan(counting breathing). It is Su(counting), Zui(Any time), Shi(stop), Kan(observe), Jo(purification).
*These steps is used in Tendai-shu.

Becoming zen mind while counting breathing. It is Su(The counting breathing)
During your counting breathing, you will realize the breathing nature of Zen mind. It is Zui.

Also, there is other steps called "The 16 method"(The steps of Shingon-shu). It is Susokukan and a Zuisokukan be the most important after all.

Therefore, Bodhidharma said "Cut the all of the waste relationship for outside. Do not exhaust your mind for inside. Enter your mind as the wall"

This proverb is including so deep meaning.

Let's try your koan with detachment. You will have enlightenment.

Go and try zen more hardly.

SD101206 Hekishusai