We assume that for all $d \geqslant 0$, $\mathbb{P}(X \in d\mathbb{Z}) < 1$, and that only finitely many $p_i$ are strictly positive. Conclude that for all $g$ of $\mathscr{F}$ piecewise continuous,
$$\sum_{k=0}^{+\infty} \mathbb{E}\left(g\left(x - S_k\right)\right) \rightarrow \frac{1}{\mathbb{E}(X)} \int_{-\infty}^{+\infty} g(t)\,dt \quad \text{when} \quad x \rightarrow +\infty$$