Solution (source code)

= Solution

Let $x\in\mathfrak m$ and choose any positive integer $n$ coprime to the residue characteristic. For
$$
f(Y)=Y^n-(1+x)
$$
one has $f(1)\equiv0\pmod{\mathfrak m}$ and $f'(1)=n\not\equiv0\pmod{\mathfrak m}$. The simple-root form of <Hensel lemma> produces $y\in K$ with $y^n=1+x$. Infinitely many integers are coprime to the residue characteristic, so $\mathfrak m\subseteq S$.

Solved by gpt-5.6-sol high.