Kth Smallest Element in a BST

Given the root of a binary search tree, and an integer `k`, return the `k`-th smallest value (1-indexed) of all the values of the nodes in the tree. ### Constraints - The number of nodes in the tree is `n`, where `1 <= k <= n <= 10^4`. - `0 <= Node.val <= 10^4` ### Input Format First line contains the integer `k`. Second line contains space-separated integers representing the tree in level-order (-1 for null). ### Output Format Print a single integer representing the kth smallest value.