struct Node  {
	int data;
	struct Node* next;
	struct Node* prev;
};

struct Node* head; // global variable - pointer to head node.


struct Node* GetNewNode(int x) {
	struct Node* newNode
		= (struct Node*)malloc(sizeof(struct Node));
	newNode->data = x;
	newNode->prev = NULL;
	newNode->next = NULL;
	return newNode;
}