Insert a node at a specific position in a linked list in C

// Program for Singly Linked List Insertion at a given position in C
#include<stdio.h>
#include<stdlib.h>

struct Node
{
  int data;
  struct Node *next;
};
// current size of Linked List
int size = 0;

void insert (struct Node **head, int data)
{
  struct Node *new_node = (struct Node *) malloc (sizeof (struct Node));

  new_node->data = data;
  new_node->next = *head;
  *head = new_node;
  size++;
}

// method to insert at a given position
void insertPosition (int pos, int data, struct Node **head)
{

  struct Node *new_node = (struct Node *) malloc (sizeof (struct Node));
  new_node->data = data;
  new_node->next = NULL;

  // Invalid positions
  if (pos < 1 || pos > size + 1)
    printf ("Invalid\n");

  // inserting first node
  else if (pos == 1)
    {
      new_node->next = *head;
      *head = new_node;
      size++;
    }

  else
    {
      struct Node *temp = *head;

      // traverse till the current (pos-1)th node
      while (--pos > 1)
	{
	  temp = temp->next;
	}
      new_node->next = temp->next;
      temp->next = new_node;
      size++;
    }
}

void display (struct Node *node)
{

  printf ("Linked List : ");

  // as linked list will end when Node is Null
  while (node != NULL)
    {
      printf ("%d ", node->data);
      node = node->next;
    }
  printf ("\n");
}

int main ()
{
  struct Node *head = NULL;

  insert (&head, 70);
  insert (&head, 60);
  insert (&head, 40);
  insert (&head, 30);
  insert (&head, 10);

  display (head);

  // Inserts data: 20 at 2nd position
  insertPosition (2, 20, &head);

  // Inserts data: 50 at 5th position
  insertPosition (5, 50, &head);

  // Inserts data: 80 at 8th position
  insertPosition (8, 80, &head);

  display (head);

  return 0;
}

Output

Linked List : 10 30 40 60 70 
Linked List : 10 20 30 40 50 60 70 80