Laplacian appliaction

\[\left\{\begin{aligned} -\Delta u &= f \quad&&\Omega \\ u&=g \quad&&\Gamma_D \\ \frac{\partial u}{\partial n} &=h \quad &&\Gamma_N \\ \frac{\partial u}{\partial n}+u &=l \quad &&\Gamma_R \\ \end{aligned}\right.\]