Notcalc (Calculate the wrong answer) Goal:
Given two natural numbers (integers from 0 to infinity), output a number that is not the sum of those numbers, but is a natural number.
Example solutions (TI-Basic):

A+B+1

not(A+B)


Invalid solutions:

A+B-1 (for inputs 0,0, it returns -1, which is not natural)

&quot;ABC&quot; (ABC is not a number)


Notes:

The output must always be a sum of two natural numbers (which is actually just a natural number)

-1, undefined, infinity, NaN and Error messages are not natural numbers. For our purposes, 0 is natural (although not all mathematicians agree).
RProgN, 4 3 1 Byte
Crossed out 4 is still 4 ;(
E

The most simple of solutions, compares if A and B are equal. Pushes true, which RProgN sees as 1, if they are the same, or false aka 0 otherwise.
Test Cases
0+0 = 1
1+0 = 0
0+1 = 0
1+1 = 1

Try it online!