Special Array With X Elements Greater Than or Equal X

You are given an array nums of non-negative integers. A special array is an array where the number of elements (n) is equal to the value of the elements (i.e., n == nums[i] for each 0 <= i < n). Return the minimum index of a special array. If there is no special array, return -1. A subarray is a contiguous subsequence of the array.