Hello! I'm taking a probability course this summer and am having a lot of trouble with this problem:

You have:

g(x,y) = {g^(x+y-1) boundary: |x-y| <= 1}

and {0 boundary: |x-y| > 1}

where g is a constant.

Find P[ M+N < 3 ].

I understand how to set up the boundaries, but I'm confused as to how to interpret g as a constant. If anyone can help, it would be greatly appreciated! Thanks!