Remove Consecutive for Balance

You are given a list of track lengths tracks and a positive integer k. Remove exactly k consecutive tracks from the list so that the sum of track lengths at even indices equals the sum at odd indices in the resulting list. Return the smallest valid starting index of the removed segment, or -1 if no such removal exists.

Indices are 0-based. The "even index sum" and "odd index sum" are computed on the resulting array after removal. ...