ps command

Shell Programming and Scripting
1

I want to extract elapsed time of the specific process. I use
ps -o etime -p${PID}

The result is 23-01:29:21 what is 23- is?
Thanks

2

from the ps man page:

etime          ELAPSED     elapsed time since the process was started, in the
                           form [[dd-]hh:]mm:ss.
3

Thank you reborg I should have got it myself ...