nodo *p0;
   arco *p1;
   for(p0=head;p0!=NULL;p0=p0->next)
   {
   	printf("%s\n",p0->nome);
   	for(p1=p0->costo;p1!=NULL;p1=p1->next)
      	printf("%.2f  %s  ",p1->prezzo,p1->citta->nome);
      printf("\n");
   }
   printf("%d",n_citta);