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

struct nodo {
  int chiave;
  struct nodo *prec, *succ;
};
typedef struct nodo nodo;

struct paridispari {
  nodo *pari;
  nodo *dispari;
};
typedef struct paridispari paridispari;

paridispari PariDispari(nodo *a);

int main() {
  nodo *first, *second, *third, *fourth, *fifth, *sixth;
  first = (nodo *) malloc(sizeof(nodo));
  second = (nodo *) malloc(sizeof(nodo));
  third = (nodo *) malloc(sizeof(nodo));
  fourth = (nodo *) malloc(sizeof(nodo));
  fifth = (nodo *) malloc(sizeof(nodo));
  sixth = (nodo *) malloc(sizeof(nodo));

  first->chiave = 1;
  first->prec = sixth;
  first->succ = second;

  second->chiave = 2;
  second->prec = first;
  second->succ = third;

  third->chiave = 3;
  third->prec = second;
  third->succ = fourth;

  fourth->chiave = 4;
  fourth->prec = third;
  fourth->succ = fifth;

  fifth->chiave = 5;
  fifth->prec = fourth;
  fifth->succ = sixth;

  sixth->chiave = 6;
  sixth->prec = fifth;
  sixth->succ = first;

  paridispari result;

  result = PariDispari(first);

  printf("%d\n", result.pari->chiave);
  printf("%d\n", result.dispari->chiave);
}

paridispari PariDispari(nodo *a) {
  paridispari result = {NULL, NULL};

  if (a == NULL) {
    result.pari = NULL;
    result.dispari = NULL;
    return result;
  }

  nodo *head_pari, *head_dispari, *current, *next_pari, *next_dispari;

  nodo *main_head;
  int i = 0;

  while (a != main_head) {

    if (a->chiave % 2 == 0) {
      if (result.pari == NULL) {
        a->prec = NULL;
        result.pari = a;
      } else {
        result.pari->succ = a;
      }
    } else {
      if (result.dispari == NULL) {
        a->prec = NULL;
        result.dispari = a;
      } else {
        result.dispari->succ = a;
      }
    }

    if (i == 0) {
      main_head = a;
      i++;
    }
    a = a->succ;
  }

  return result;
}