$j \in \{n_1+1, \ldots, n-1\}$ and that $r_j, l_j$ for $j \in
\{1, \ldots, n\}$ and $L$ are integers.

Reclaimers start and finish at the two endpoints of the rail, reclaimer $R_0$ at point $0$ and reclaimer $R_1$ at point $L$, and can reclaim stockpiles on either one of the pads (we assume there is no time required to switch from one pad to the other), but they cannot pass each other. A reclaimer can stay idle or move forward and backward at the given speed $s$. When reclaiming a stockpile the speed cannot be larger than $s$. Without loss of generality, we assume that the reclaim speed is equal to 1 and the travel speed is $s\geqslant 1$. Thus, the time necessary to reclaim stockpile $j$ is $p_j = r_j - l_j$, the length of stockpile $j$.

When the positions of the stockpiles are not given but have to be decided, we are given the length $p_j \in {\mathbb{Z}}$ of each stockpile $j$ ($0 < p_j \leqslant L$) and we have to decide the pad on which to locate the stockpile (either $P_1$ or $P_2$), the position $(l_j,
r_j)$ of that pad that the stockpile will occupy, and the 