Question 6
(GDR 2) Let $n$ be a positive integer. How many integer solutions $(i,j,k,l)$, $1\le i,j,k,l\le n$, does the following system of inequalities have:
$$\begin{aligned}1&\le-j+k+l\le n\\1&\le i-k+l\le n\\1&\le i-j+l\le n\\1&\le i+j-k\le n\ ?\end{aligned}$$
$$\begin{aligned}1&\le-j+k+l\le n\\1&\le i-k+l\le n\\1&\le i-j+l\le n\\1&\le i+j-k\le n\ ?\end{aligned}$$