Delete a Node at a given Position in a Linked List in C++

// Linked List deletion at a given position in C++
#include< iostream>
using namespace std;

class Node
{
public:
    int data;
    Node *next;
};

// Current size of Linked List
int size = 0;

void insert(Node **head, int data)
{
    Node *new_node = new Node();
    new_node->data = data;
    new_node->next = *head;
    *head = new_node;
    ::size++; // Use the global variable 'size'
}

void deletePosition(int pos, Node **head)
{
    Node *temp = *head;
    Node *prevNode;

    if (pos < 1 || pos > ::size) // Use the global variable 'size'
    {
        cout << "Invalid" << endl;
        return;
    }

    // Delete the 1st node
    if (pos == 1)
    {
        *head = (*head)->next;
        cout << temp->data << " deleted" << endl;
        delete temp;
        ::size--; // Use the global variable 'size'
        return;
    }

    // Traverse to the pos'th node
    while (--pos)
    {
        prevNode = temp;
        temp = temp->next;
    }
    
    // Change prevNode node's next node to nth node's next node
    prevNode->next = temp->next;

    // Delete this nth node
    cout << temp->data << " deleted" << endl;
    delete temp;
    ::size--; // Use the global variable 'size'
}

void display(Node *node)
{
    cout << "Linked List: ";

    // As linked list will end when Node is Null
    while (node != NULL)
    {
        cout << node->data << " ";
        node = node->next;
    }
    cout << endl;
}

int main()
{
    Node *head = NULL;

    insert(&head, 100);
    insert(&head, 80);
    insert(&head, 60);
    insert(&head, 40);
    insert(&head, 20);

    display(head);

    // Delete the 2nd node
    deletePosition(2, &head);

    // Delete the 4th node
    deletePosition(4, &head);

    display(head);

    return 0;
}