Singly Linked List Insertion

#include<stdio.h>
#include<stdlib.h>
struct node
{
int data;
struct node *next;
};
struct node *head = NULL;
struct node *tail = NULL;
void addnode(int data);
int countnode();
void display();
void insertnode(int ip,int data);
int main()
{
  int n,num,i=0,ip;
  printf("Enter the number of nodes required in linked  list: ");
  scanf("%d",&n);
  while(i!=n)
    {
      printf("Enter data in node %d: ",(i+1));
      scanf("%d",&num);
      addnode(num);
      i++;
    }
  printf("\nThe number of nodes in the list is %d\n",countnode());
  display();
  printf("\nEnter the position at which you want to insert new node: ");
  scanf("%d",&ip);
  printf("Enter the data to be inserted in new node: ");
  scanf("%d",&num);
  insertnode(ip,num);
  printf("\nThe number of nodes in the list is %d\n",countnode());
  display();
}
void addnode(int data)
{
  struct node *newnode = (struct node *)malloc(sizeof(struct node));
  newnode->data= data;
  newnode->next= NULL;
  if(head == NULL)
  {
    head = newnode;
    tail = newnode;
  }
  else
  {
    tail->next=newnode;
    tail = newnode;
  }
}
int countnode()
{
  int count=0;
  struct node *current = head;
  while(current !=NULL)
    {
      count++;
      current = current->next;
    }
  return count;
}
void display()
{
  struct node *current = head;
  while(current != NULL)
    {
      printf("%d ",current->data);
      current = current->next;
    }
}
void insertnode(int ip,int data)
{
  struct node *newnode = (struct node *)malloc(sizeof(struct node));
  struct node *temp;
  struct node *ptr = head;
  if(ip == 1)
  {
    newnode->data = data;
  newnode->next = head;
    head = newnode;
  }
  else
  {
  for(int i=1;i<ip-1;i++)
    {
      ptr = ptr->next;
    }
  temp = ptr->next;
  ptr->next = newnode;
  newnode->data = data;
  newnode->next = temp;
  }
}