Using Replace to remove unspecified amount of letters

[Family Lieberman]

I am a teacher.  I have an excel file of all students written as Lastname, Firstname  for example Smith, John or Walker, Martin.  How can I use the replace command to change each cell so that it only contains the last name, the comma, and ONLY THE FIRST LETTER of the first name i.e. Smith, J    Walker, M

Thank you

[#2]

Hi,

Flash Fill works http://www.dummies.com/software/microsoft-office/excel/how-to-use-flash-fill-in-excel-2013/

[#3]

Thank you so much! Worked amazingly after I spent so much time trying to use the Replace command with * and ? that just didn't work. Thanks for taking the time to answer.