I am trying to figure which formula to use for the following type of
scenario. I've simplified it to make it easier to understand the concept.

Column A has a five digit "group" number followed by dash and another five
"individual" number (ex: 12345-67890). However, the first five digits are not
all the same because there are multiple "group" numbers.

I want to be able to create a formula in Column B that analyzes the first
five numbers in Column A, and yield "Blue" or "Red".

If the first five numbers are either "12345" or "23456", I want the formula
to yield "Blue" in Column B.

If the first five numbers are "34567" or "45678", I want the formula to
yield "Red" in Column B.

Which formula should I use and how would I write it? THANKS!