#ifndef _COLLATZ_H_
#define _COLLATZ_H_

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


typedef struct {
    list *first;
    int qty;
} header;

typedef struct {
    int val;
    list *next;
} list;

typedef header* listADT;

listADT
makeList()
{
    listADT ans;
    ans = malloc(sizeof(header));
    ans->first = NULL;
    ans->qty = 0;
    return ans;
}

bool
isEmpty(listADT list)
{
    return list->qty==0;
}


void
addToList(listADT list, int n)
{
    if (list->first == NULL) {
        list->first->val = n;
    }

    (algo)
}