BstNode* Insert(BstNode* root, int data)
{
    if(root==NULL)
    {
        root = GetNewNode(data);
    }
    else if(data <= root->data)
    {
        root->left = Insert(root->left, data);
    }
    else
    {
        root->right = Insert(root->right, data);
    }
    return root;
}