Node* insert(Node *head,int data)
      {
          //Complete this method          
          Node *dummyNode = new Node(0);
          dummyNode->next = head;
          Node *newNode = new Node(data);
          Node *current = dummyNode;
          
          while (current->next != NULL) {
            current = current->next;
          }
          current->next = newNode;
          return dummyNode->next;
      }