22. Let $S$ be the set of all non-zero real-valued functions $f$ defined on the set of all real numbers such that
$$
\mathrm{f}\left(x^{2}+y f(z)\right)=x \mathrm{f}(x)+z \mathrm{f}(y)
$$
for all real numbers $x, y$ and $z$. Find the maximum value of $\mathrm{f}(12345)$, where $\mathrm{f} \in S$.