The largest value of the nonnegative integer $a$ for which $$\lim_{x \rightarrow 1} \left\{\frac{-ax + \sin(x-1) + a}{x + \sin(x-1) - 1}\right\}^{\frac{1-x}{1-\sqrt{x}}} = \frac{1}{4}$$ is
The largest value of the nonnegative integer $a$ for which
$$\lim_{x \rightarrow 1} \left\{\frac{-ax + \sin(x-1) + a}{x + \sin(x-1) - 1}\right\}^{\frac{1-x}{1-\sqrt{x}}} = \frac{1}{4}$$
is