How do I convert a 50 column table to a 4 column table?

I have a database that works as follows:

Column Headers:

ID Last Name First Name Position 1 Position 2 Position 3 Position 4 Position 5 Position 6 etc…

Each employee might have up to twenty positions, each marked in a cell with an X.

With over 120 rows and roughly 50 columns, I need to convert them into this type of format:

Row Headers:

ID Last Name First Name Position

So for each employee, they might have 10 to 20 entries. It’s rediculous, but it’s the only usable format for the data I can use. Currently I’m sorting the columns by a particular position and copy and pasting into a new spreadsheet. Any ideas for how to automate the process?