Find the smallest possible value of the expression $$\frac{(a+b)^2+(b-c)^2+(c-a)^2}{b^2},$$where $b > c > a$ are real numbers, and $b \neq 0.$The answer is in the form rac{m}{n}, where gcd(m, n) = 1. Please provide the value of m + n.

Let's think step by step and output the final answer within \boxed{}.
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