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