Careless Chef

Chef has a sequence of integers $A$ of length $N$. He creates another sequence $B$ of length $2 \cdot N$ using sequence $A$. Initially, $B$ is empty. Chef performs the following process. For each element $A_i$ $(1 \le i \le N)$ of $A$: - Choose any arbitrary integer $k$ (Note that the value of $k$ can be different for different elements). - Add $A_i-k$ and $A_i+k$ to $B$. Chef then shuffles the