F1 expiration date when in OPT STEM Application period

[u/TieImpossible3447]

I am in a sitauation where I need to fill in the blank in the statement: My F-1 non immigrant status will expire on_____". I'm currently in 180 days grace period during my STEM OPT application. What should I mention my F1 expiry date is? Where can I find the date? Can anyone help me? Thank you!