27. 已知函数f(x)={∣lg∣x−1∣∣,x≠10,x=1f(x)=\left\{{\left.\begin{array}{l}{\vert lg\vert x-1\vert \vert ,x\ne 1}\\ {0,x=1}\end{array}\right.}\right.f(x)={∣lg∣x−1∣∣,x=10,x=1，则函数y=f(f(x))+m(m∈R)y=f(f(x))+m(m\in R)y=f(f(x))+m(m∈R)零点个数最多是((( )))