Question 21
(CZS 2) Let $a_0,a_1,\ldots,a_k$ $(k\ge1)$ be positive integers. Find all positive integers $y$ such that
$$a_0\mid y;\qquad(a_0+a_1)\mid(y+a_1);\qquad\ldots;\qquad(a_0+a_n)\mid(y+a_n).$$
$$a_0\mid y;\qquad(a_0+a_1)\mid(y+a_1);\qquad\ldots;\qquad(a_0+a_n)\mid(y+a_n).$$