#include <cstdlib>
#include <iostream>
#include <fstream>
#include <algorithm>
#include <sstream>
using namespace std;

struct Node {
int val;
Node * next;
};

class List {
private:
Node * head;
Node * tail;
int size;
public:

List() {
   head = 0;
   tail = 0;
   size = 0;
};

~List() {
   Node * n = head;
   Node *t;
   while (n != 0) {
         t = n;
         n = n->next;
         delete t;
   }
}

/**
* append(parameter one is the object to be added):
* append the object at the end of the list
* @param val
*/
void append(int val) {
   Node * n = new Node;
   n->next = 0;
   n->val = val;
   if (head == 0) { // basic case
         head = n;
         tail = n;
   } else { // normal case
         tail->next = n;
         tail = n;
   }
   size++;
}

/**
* add(parameter one is the object to be added,
* parameter two is the position starting from 0)
* @param val
* @param position
*/
void add(int val, int position) {
   if (position < 0) {
         return;
   }
   if (head == 0) { // basic case
         append(val);
   } else { // normal case
         int index = 0;
         Node * curr = head;
         Node * pre;
         Node * n = new Node;
         n->next = 0;
         n->val = val;
         if (position == 0) { // add to head
            n->next = head;

You are going to implement a program that creates an unsorted list...