\begin{frame}{Exercise}
  \begin{exampleblock}{}
    Given is the following NFA:
    \begin{center}
      \vspace{-.5ex}
      \input{tikz/nfa1.tex}
      \vspace{-1.5ex}
    \end{center}
    \emph{Construct an NFA that accepts the reverse language:}
    \pause
    \begin{center}
      \vspace{-.5ex}
      \begin{tikzpicture}[default,node distance=20mm,->]
        \node (q0) [fstate] {$q_0$}; 
        \node (q1) [state,right of=q0] {$q_1$}; \draw ($(q1) + (-7mm,7mm)$) -- (q1); 
        \node (q2) [fstate,right of=q1] {$q_2$}; 
        
        \draw [<-] (q0) to[bend left=10] node [label,above] {$a$} (q1);
        \draw [<-] (q0) to[bend left=-10] node [label,below] {$\lambda$} (q1);
        \draw [<-] (q1) to[bend left=0] node [label,above] {$b$} (q2);
        \draw (q1) to[out=40,in=100,looseness=5] node [label,above right] {$b$} (q1);
        \draw [<-] (q2) to[out=-130,in=-50,looseness=0.5] node [label,below] {$a$} (q0);
      \end{tikzpicture}
    \end{center}
  \end{exampleblock}
\end{frame}