$, then $o_r^\prime=o_r+0>     e_r-0=e_r^\prime$ and $$\begin{aligned}     \kappa(\mathcal{C})&=o_s+0e_s+o_r,\\     \kappa(\mathcal{C}')&=o_s+0e_s-0+o_r^\prime=o_s+0e_s+o_r=\kappa(\mathcal{C}).\end{aligned}$$  