3000. What character can be added to both of these characters to give other characters? 串_ -> _中

串 KEN, KAN, kushi - skewer

中 CHUU, naka - middle, medium

Add 心:串+心 心+中

心 SHIN, kokoro - heart

患 KAN, wazura(u) - be ill, suffer from

忠 CHUU - loyalty, faithfulness