885. Kth Smallest Element in BST

Given the root of a binary search tree and an integer k (1-indexed), return the k-th smallest key in the BST. The input gives a level-order BST array and k separated by ' | '.

Input: A level-order BST array and k, separated by ' | '.

Output: Integer — the k-th smallest key.

Examples

Input: [8,3,10,1,6,null,14] | 3
Output: 6
Explanation: Sorted keys; 3rd smallest is 6.

Input: [4,2,7,1,3] | 1
Output: 1
Explanation: Smallest key.

Input: [5] | 1
Output: 5
Explanation: Single node.

Constraints

• 1<=k<=nodes<=10^4
• valid BST

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