/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class BSTIterator {
    private Stack<TreeNode> path;
    private Stack<Character> operations;

    public BSTIterator(TreeNode root) {
        path = new Stack<TreeNode>();
        operations = new Stack<Character>();

        path.push(root);
        operations.push('L');
    }

    /** @return the next smallest number */
    public int next() {
        char operation = operations.peek();
        switch (operation) {
            case 'L':
                TreeNode left = path.peek().left;
                if (left != null) {
                    path.push(left);
                    operations.push('L');
                }
                break;
            case 'M':
                break;
            case 'R':
                break;
        }
        return 0;
    }

    /** @return whether we have a next smallest number */
    public boolean hasNext() {
        return false;
    }
}

/**
 * Your BSTIterator object will be instantiated and called as such:
 * BSTIterator obj = new BSTIterator(root);
 * int param_1 = obj.next();
 * boolean param_2 = obj.hasNext();
 */