I need some help in coming up with a formula that would do the following:

Basically (refer to the screenshot below) I need a formula for Column W that would post a number 1 whenever Column O is not "-" and then continue counting until Column T posts a "Flip" text.
In the screenshot below, I've shown an example of what I want the formula to display (only this time I've manually entered the Count).
Since I'm dealing with over 20 Years of data, I'd appreciate if someone could suggest a formula for this as opposed to me doing it manually.

Thanks in advance!

screenshot.jpg