button with an X at the upper-right corner of the form, how to catch this event @ C#

[C# Programming]

End Google Ads 201810 - BS.net 01 --> hello,

which event is fired when i close form with X button ? i want event that fired only with X button pressed, i know that there is a FormClosing event, but the problem is that it fires each time when form is closed... also with frm.close()

and i don't want that happen

tanx