algebra

(x-y) + 1

123:

(x-y) + 1

almost..
x=5
y=4
(x-y) + 1 = (5-4)+1 = 2

but:
x=4
y=5
(x-y) + 1 = (4-5)+1 = 0 (not correct)

modified formula:
abs(x-y) + 1

x=4
y=5
(x-y) + 1 = abs(4-5)+1 = abs(-1) + 1 = abs(1) +1 = 2