3. Given numbers $x_{1}, \ldots, x_{n} \in(0,1)$. Find the maximum value of the expression

$$
A=\frac{\sqrt[4]{1-x_{1}}+\ldots+\sqrt[4]{1-x_{n}}}{\frac{1}{\sqrt[4]{x_{1}}}+\ldots+\frac{1}{\sqrt[4]{x_{n}}}}
$$