Inverse Trigonometric Functions

For the least possible value of $n \in \mathbf{Z}$ the solution $(x, y)$ of the equations $\cos ^{-1} x+\left(\sin ^{-1} y\right)^2=\frac{n \pi^2}{4}$ and $\cos ^{-1} x\left(\sin ^{-1} y\right)^2=\frac{\pi^4}{16}$, is