Find the longest contigous subsequence where each pair's difference is at most p

Question

Given input sequence $x_1,...,x_n$, find the longest contigous subsequence $x_i,... x_l$ where each pair $(x_j,x_k)$ satisfies that $|x_j - x_k| \le p$.

I have come up with simple $\mathcal{O}(n^2)$ solution.

I'm sure there is a better way so I'm looking for $\mathcal{O}(n)$ or at least $\mathcal{O(n \log n)}$ solution. Thanks for any help!