struct tree_node {
	string data;
	tree_node *left = 0, *right = 0;
};

tree_node* find_parent(string child_data, tree_node *root){
	if(!root)
		return 0;
	if(root->data == child_data)
		return 0;
	if(child_data > root->data){
		if(root->right->data == child_data)
			return root;
		return find_parent(child_data, root->right);
	}
	if(root->left->data == child_data)
		return root;
	return find_parent(child_data, root->left);
}