Binary Search Tree construction from unsorted list of integers

#include<iostream>
#include <cstdio>
#include <cstdlib>
#include <string>
#define M 10
using namespace std;

class Node
{
public:
    int data;
    struct Node* left;
    struct Node* right;
};

Node *bstInsert(Node *root, int data);
void displayTree(Node *root);
void displayNode(Node *root);

int main(int argc, char **argv)
{
    int num, n = 0;

    freopen("in.txt","r",stdin);

    Node *root1 = NULL;
    while (scanf("%d", &num) == 1)
    {
        root1 = bstInsert(root1, num);
    }

    displayTree(root1);
    return 0;
}  

Node *bstInsert(Node *root, int data)
{
    if (root == NULL)
    {
        root = new Node();
        root->data = data;
        root->left = root->right = NULL;
    }
    else if (data < root->data)
        root->left = bstInsert(root->left, data);
    else
        root->right = bstInsert(root->right, data);
    return root;
}

void displayTree(Node *root)
{
    if (root == NULL) {
        return;
    }
   
    cout<<"Root: "<<root->data;
    if(root->left != NULL)
    {
        root->left->data;
        cout<<", Left: "<<root->left->data;
    }

    if(root->right != NULL)
    {
        cout<<", Right: "<<root->right->data;
    }
    cout<<endl;
    displayTree(root->left);
    displayTree(root->right);
}

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