Functions

Let $f: R \rightarrow R$ be a function defined by

$$ f(x)=\left\{\begin{array}{cc} x^2-4 x+3, & \text { if } x<2 \\ x-3, & \text { if } x \geq 2 \end{array}\right. $$

Then, the number of real numbers $x$ for which $f(x)=8$ is