Let $\underline{A}\ \underline{B}\ \underline{C}$ represent a three-digit base 10 number whose digits are $A$, $B$, and $C$ with $A \ge 1$. Compute the minimum value of$$ \underline{A}\ \underline{B}\ \underline{C} - (A^2 B^2 C^2). $$