void swapElement(int i, int j) {
    struct Node* ptr = first;
    struct Node* prev_ptr = first;

    struct Node* j_left = first;
    struct Node* j_ = first;
    struct Node* j_right = first;

    struct Node* i_left = first;
    struct Node* i_ = first;
    struct Node* i_right = first;

    struct Node* t_ = first;

    int index = 0;
    while (ptr != NULL) {
        if (index == i) {

            i_ = ptr;
            i_right = ptr->next;
        }

        if (index == j) {

            j_ = ptr;
            j_right = ptr->next;
        }

        prev_ptr = ptr;
        ptr = ptr->next;
        index++;
    }

    //t_ = i_left;
    //i_left = j_left;
    //j_left = t_;

    //t_ = i_right;
    //i_right = j_right;
    //j_right = t_;

    ptr = first;
    index = 0;
    while (ptr != NULL) {

        if (index == i) {
            ptr = j_;
            ptr->next = i_right;
        }


        if (index == j) {
            ptr = i_;
            ptr->next = j_right;
        }

        ptr = ptr->next;
        index++;
    }
}



void  main() {
    printList();

    addToHead(1);
    addToHead(3);
    addToHead(6);
    addToHead(7);
    addToHead(8);
    addToHead(12);
    printList();

    swapElement(2, 4);
    printList();

    clearList();
    printList();

    {
        int x;
        scanf("%d", &x);
    }
}