Sed Max

JJ has a magical sequence $A_1, A_2, \ldots, A_N$. The group of high magicians Sed wants to buy this sequence from him. They calculate its cost as follows: - Choose a subarray of length atleast $2$, i.e. a contiguous subsequence $A_l, A_{l+1}, \ldots, A_r$ such that $1 \le l \lt r \le N$. - The cost is the difference between the largest and the second largest element in this subarray (note that