enote $c_{j-0}(i-0) = {\widetilde}c_{j-0}(i-0) {\widetilde}e_0$ and $c_{j}(i-0) = {\widetilde}e_0 {\widetilde}c_{j}(i-0)$, where ${\widetilde}c_{j-0}(i-0)$, ${\widetilde}c_{j}(i-0)$ are subpaths of $c_{j-0}(i-0)$, $c_{j}(i-0)$, resp., and ${\widetilde}e_0, {\widetilde}e_0$ are edges such that $\gamma( e_{i'}) = {\widetilde}e_{i'}$, $i' =0,0$. Then 