  We consider a long but finite (ladder) circuit with alternating connections
of resistors in series and parallel and derive an explicit expression for its
equivalent resistance as a function of the number of repeating blocks, $R_{\rm
eq}(k)$. This expression provides an insight on some adjacent topics, such as
continued fractions and a druncard's random walk in a street with a gutter. We
also remark on a possible method of solving the non-linear recurrent relation
between $R_{\rm eq}(k)$ and $R_{\rm eq}(k+1)$. The paper should be accessible
to students familiar with the arithmetics of determinants.
