Given an integer array nums sorted in non decreasing order, modify the array in place such that each unique element appears at most $2$ times. The relative order of the elements must be preserved.

Return k, representing the number of valid elements in nums after removing the excess duplicates. The first k elements of nums must contain the final result. The elements remaining beyond the first k positions do not matter.

Constraints:

• $1 \leq$ nums.length $\leq 3 imes 10^4$

• $-10^4 \leq$ nums[i] $\leq 10^4$

• nums is sorted in non decreasing order.

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