\begin{logicproof}{2}
    \lnot\psi & \prem \\
    \varphi \imp \psi & \prem \\
    \begin{subproof}
        \varphi & \assum \\
        \psi    & $\impe 1,2$ \\
        \bot    & $\nege 1,4$
    \end{subproof}
    \lnot\varphi & $\negi 3-5$
\end{logicproof}