心机 
心机[-機] ¹xīnjī* {E} n. thinking; scheming
费尽心机 费尽心机 [fèijìnxīnjī] to rack one's brains for schemes (idiom); to beat one's brains out 
費 费 expense / - / dollar money expense 尽 尽 exhaust / - / shaku ice exhaust 心 心 heart / - / - heart 機 机 mechanism / - / tree abacus mechanism