Is there a formula I can use to subtotal column data instead of using the
subtotal feature?

When I try using the subtotal feature it puts the subtotal at the bottom of
data. I would like to subtotal $ data located in Column M and N for each
change in a person's name in Column C. I would like this subtotal to show in
column O on the first row of each change in column C like this:

Column C Column M Column N Column O
John Smith 100.00 500.00
John Smith 300.00
John Smith 30.00
John Smith 70.00
Joe Bird 300.00 750.00
Joe Bird 30.00
Joe Bird 175.00
Joe Bird 245.00


Thank you in advance for your reply! :)