Need Help

#include <stdio.h>
#include <stdlib.h>
struct node
{
    int data;
    struct node *link;
} * head;

void create(int n);
void add(int data);
void display();
int main()
{
    struct node *head;
    int n, data;
    printf("HOW MANY NODES DO YOU WANT : ");
    scanf("%d", &n);
    create(n);
    printf("Data in the list : \n");
    display();

    printf("\nenter the data you want to inseart in the end: ");
    scanf("%d", &data);
    add(data);
    printf("THE FINAL LIST ");
    display();
    return 0;
}
void create(int n)
{
    head = (struct node *)malloc(sizeof(struct node));
    struct node *temp = (struct node *)malloc(sizeof(struct node));
    struct node *newnode = (struct node *)malloc(sizeof(struct node));
    int i, data;

    if (head == NULL)
    {
        printf("memory problem");
    }
    else
    {
        printf("1 NO data : ");
        scanf("%d", &data);
        head->link = NULL;
        head->data = data;
        temp = head;
        if (newnode == NULL)
        {
            printf("memory problem:");
        }
        else
        {
            for (i = 2; i <= n; i++)
            {
                printf("%d no-- data : ", i);
                scanf("%d", &data);
                newnode->data = data;
                newnode->link = NULL;

                temp->link = newnode;
                temp = temp->link;
            }
            //printf("data entry successful");
        }
    }
}
void add(int data)
{
    struct node *newnode = (struct node *)malloc(sizeof(struct node));
    struct node *temp;
    newnode->data = data;
    newnode->link = NULL;
    temp = head;

    while (temp->link != NULL)
    {
        //printf("%d no data is : %d",i,temp->data);
        temp = temp->link;
    }
    temp->link = newnode;
    printf("DATA ENTWER SUCCECC\n");
}
void display()
{

    struct node *temp;
    if (head == NULL)
    {
        printf("display error\n");
    }
    else
    {
        int count = 1;
        temp = head;
        while (temp!= NULL)
        {
            printf("%d no data = %d \n", count, temp->data);
            temp = temp->link;
            count++;
        }
    }
}