binary tree

#include <iostream>
#include <fstream>

using namespace std;

struct Node
{
    string tel; //ключ
    string name;

    int step;

    Node* left;
    Node* right;
};

void print(Node* root)
{
    if (root != NULL)
    {
        cout << root->step << ": " << root->tel << endl;
        //cout << "Телефон: " << root->tel << "; Имя: " << root->name << endl;
        //cout << "влево ";
        print(root->left);
        //cout << "вправо ";
        print(root->right);
    }
    else {
        //cout << " конец ветки " << endl;
    }
}

Node* add(string tel, string name, Node* root, int step = 0)
{
    if (root == NULL)
    {
        root = new Node;
        root->tel = tel;
        root->name = name;

        root->left = NULL;
        root->right = NULL;

        root->step = step;
    }
    else if (tel < root->tel)
    {
        //cout << "<- ";
        step += 1;
        root->left = add(tel, name, root->left, step);
    }
    else
    {
        step += 1;
        root->right = add(tel, name, root->right, step);
    }
    return root;
}

int main()
{
	setlocale(0, "rus");

    Node* tree = NULL;
    tree = add("10000000001", "Вася", tree);
    tree = add("11000000000", "Вася", tree);
    tree = add("10000000010", "Вася", tree);
    tree = add("10000000100", "Вася", tree);
    tree = add("10000000000", "Вася", tree);
    tree = add("11100010000", "Вася", tree);
    tree = add("10000010000", "Вася", tree);
    tree = add("1000000000", "Вася", tree);

    print(tree);

	system("pause");
	return 0;
}