You are right, this seems to only exist in .net core 2.0 and forward. https://docs.microsoft.com/en-us/dotnet/api/system.string.split?view=netcore-2.0#System_String_Split_System_String_System_StringSplitOptions_

are your solution with .net core?
.net framework 4.x doesn't contains String.Split(string, ...)

Aaah, nice one. I attempted something similar but I had to add an extra filtering step to get rid of empty entries. Now I understand how I could have done it better!

That's certainly an interesting existential quandary.

So in what kind of universe can you occupy a place among "p" number of people where you can have more than "p" number of people standing before you?

If such universe indeed exists, "should" we denote such circumstance as having zero number of people before you? I mean, should it even matter what we call anything at that point?

But you are right.

Use of uint might have been more appropriate.

if (p-bef < 0)
then the result should be 0

Ha ha. It is a code war indeed.