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

typedef struct ListNode {
   int data;
   struct ListNode *next;
} ListNode;

int main() {

   printf("hello world!\n");

   ListNode *head = NULL;

   for (int i = 0; i < 5; i++) {
      ListNode *p = (ListNode *) malloc (sizeof(ListNode));
      p->data = i;
      p->next = head;
      head = p;
   }
   
   ListNode *p = head;
   while (p != NULL) {
      printf("node... %d\n", p->data);
      p = p->next;
   }

   for (ListNode *p = head; p != NULL; p = p->next)
      printf("node2... %d\n", p->data);

}