IMORf:RRxyf(f(x)f(y))+f(x+y)=f(xy)IMOPxyP00f(f(0)^2=01x1yx+y=xyy=xx-1Pxxx-1f(f(x)f(xx-1))=0x12f0IMOnAA=A0+A1+A2A0=aInaA1A2AntrA=0PP^-1AP0nn=1A=0n2RnA