How to unite value in the same column

I have an example with two columns (Name, Region), column (Segment) is the result I have solved.

The condition for column "Segment" is IF(AND(John = "North", John ="South", "John"=Centre"), "N-S", IF(OR(AND(John = "North", "John"=Centre"), John="North"), "N", IF(John="South", "S")))
I can't find any way to solve this problem.
I hope anyone can help me. Thanks!