2759. What character can be added to both of these characters to give other characters? 麻_ -> _更

麻  MA, asa - hemp, flax

更  KOU, sara, fu(kasu), fu(keru) - anew, again, grow late

Add 石:麻+石 石+更   

石  SEKI, SHAKU, ishi - stone

磨  MI, miga(ku) - polish, brush

硬  KOU, kata(i) - hard, firm