Given an integer array nums, return the length of the longest arithmetic subsequence in nums.

A subsequence is a sequence obtained from nums by deleting zero or more elements without altering the relative order of the remaining elements.

A sequence seq is arithmetic if the difference between any two consecutive elements is constant.

Constraints:

• $2 \le$ nums.length $\le 1000$

• $0 \le$ nums[i] $\le 500$

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