Delete a length-k subarray to minimize the smallest valid index (sliding window variant)

Problem (Sliding Window Variant) You are given an integer array arr of length n and an integer k. You must delete exactly one contiguous subarray of length k from arr. The remaining elements keep their relative order and are concatenated into a new array. After deletion, you need to find the minimum valid index in the resulting array (the exact definition of valid index follows the original problem statement; this interview note references a variant and does not fully specify the validity rule). Output the minimum valid index achievable by deleting some length-k contiguous block. Input Line 1: two integers n and k Line 2: n integers representing arr Output A single integer: the minimum valid index after deleting a length-k block (or the designated value such as -1 if no valid index exists, per the original definition). Constraints 1 <= n <= ? 0 <= k <= n arr[i] range: ? Examples Placeholder only because the valid index definition is missing. input: 5 2 1 2 3 4 5 output: ? input: 3 1 2 2 2 output: ?