I have four columns below is the example

Name Qty Name Qty
John 4 Scott 3
Jim 3 John 2
Jake 2 Jim 1

What I need to do is compare "Name" column and take the difference between
the "Qty column

Result would be John 2, Jim 2, Jake 2, Scott -3

Any help would be great, not looking to sort because I have lots of data.
Guessing Index Match, but can't get it to work