Tree traverse

#include<bits/stdc++.h>
using namespace std;
class Node{
public:

    int key;
    Node *left;
    Node *right;
    Node( int k)
    {
        key = k;
        left = right = NULL;
    }
};
class Tree{
public:
    Node *root;
    void printInorder( Node *temp )
    {

        if( temp == NULL){
            return;
        }
        printInorder( temp -> left);
        cout<<temp->key;
        printInorder( temp -> right);
    }
};
int main()
{
    Node *n1 = new Node(1);
    Node *n2 = new Node(2);
    Node *n3 = new Node(3);
    Node *n4 = new Node(4);
    Node *n5 = new Node(5);

    Tree *t = new Tree();
    t -> root = n1;
    t -> root -> left = n2;
    t -> root ->right = n3;
    t -> root -> left -> left = n4;
    t -> root -> left -> right = n5;

    t ->printInorder(n1);
    return 0;
}