$$N=\frac{1}{2}+I\frac{2}{L}$$
$I=\frac{L\left(2N-1\right)}{4}$
$L\neq 0$
$\left\{\begin{matrix}L=-\frac{4I}{1-2N}\text{, }&I\neq 0\text{ and }N\neq \frac{1}{2}\\L\neq 0\text{, }&N=\frac{1}{2}\text{ and }I=0\end{matrix}\right.$