When I use `git rev-list --count HEAD` revision as part of my EXE's version info...

I wonder how to find the commit when I only have the count value.

For instance,
`git rev-list --count HEAD` returns 50 and the commit is "abcdefg...."

With the commits growing, use `git rev-list --count HEAD` again and return 100,

How can I use **50** to find "abcdefg...." easily?

I try to find the answer but I didn't find out any clue.

Thanks