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 public int kthSmallest(TreeNode root, int k) {
    List<Integer> nums = new ArrayList<>();

    find_num(root, nums, k);

    return nums.get(k-1);
}
public void find_num(TreeNode root, List<Integer> nums, int k){
    if(root != null){
        find_num(root.left, nums, k);
        nums.add(root.val);
        if(nums.size() == k){
            System.out.print(root.val + "here \n");
            return;
        }
        find_num(root.right, nums, k);
    }
}