Given an array of integers, nums, and an integer k, find the maximum sum of two elements in nums less than k. Otherwise, return $−1$ if no such pair exists.

Constraints:

• $1\leq$ nums.length $\leq100$

• $1\leq$ nums[i] $\leq 10^3$

• $1\leq$ k $\leq 10^3$