2790. What character can be added to both of these characters to give other characters? 山_ -> _少

山  SAN, yama - mountain

少  SHOU, suku(nai), suko(shi) - little, few

Add 石:山+石 石+少  

石  SEKI, SHAKU, ishi - stone

岩  GAN, iwa - rock

砂  SA, SHA, suna - sand