A list of integers 
are arranged on a whiteboard.
At each stage, two numbers 
and 
are removed from the whiteboard and replaced with the single number 
.
This process is continued until there is only one number remaining on the whiteboard.
What is this number?
Prove that your answer is the same for all a, b.
As a reminder, we will unfortunately not be giving any credit to proofs solely by exhaustion (For example, simply brute forcing all elements in Python with no mathematical explanation). Brute-force is only acceptable for problems that don’t require a proof. Happy problem solving!