#include <stdlib.h>
#include <stdio.h>

struct node {
 int data;
 unsigned long ptrOffset;
};

struct xorList {
    struct node* head;
    struct node* tail;
};

struct xorList* InitList(int data, int data2) {
 struct node* head = malloc(sizeof(struct node));
 struct node* tail = malloc(sizeof(struct node));
 head->ptrOffset = (unsigned long)((unsigned long)NULL ^ (unsigned long)tail);
 head->data = data;
 tail->ptrOffset = (unsigned long)((unsigned long)head ^ (unsigned long)NULL);
 tail->data = data2;
 struct xorList* list = malloc(sizeof(struct xorList));
 list->head = head;
 list->tail = tail;

 return list;
}

void Append(struct node* head, struct node* tail, int data) {
 struct node* newNode = malloc(sizeof(struct node));

 newNode->ptrOffset = (unsigned long)((unsigned long) head ^ (unsigned long)tail);
 newNode->data = data;
}

void main(){
 struct xorList* list = InitList(1, 2);
 //Append(head, 2);
 int count = 0;
 struct node* current = list->head;
 struct node* begin = list->head;
 struct node* prev = NULL;
 while (current != NULL) {
  count++;
  if (current == begin) {
   current = (struct node*)((unsigned long)prev ^ current->ptrOffset);
  }
  else {
   current = (struct node*)((unsigned long)prev ^ current->ptrOffset);
  }
 }
 printf("%d", count);
}