doubly linked list

#include<stdio.h>
#include<stdlib.h>
typedef struct node
{
    int a;
    struct node*next,*prev;
} node;


node*head=NULL,*tail=NULL;

int main()
{
    int ch;
    while(1)
    {
        printf("\n\nDoubly linked list operations\n\n");


        printf("1.Insert First\n");
        printf("2.Insert Any\n");
        printf("3.Delete Elements\n");
        printf("4.display\n");
        printf("5.Delete Position\n");
        printf("6.Search Data\n");
        printf("7.Insert at end\n");
        printf("8.display_last\n");
        printf("Enter your choice:");

        scanf("%d",&ch);

        switch(ch)
        {
        case 1 :
            Insert_first();
            break;
        case 2:
               insert_any();
            break;
        case 3 :
            delete_data();
            break;
        case 4:
            display_first();
            break;
        case 5:
            Delete_Position();
            break;
        case 6:
            Search_Data();
            break;
        case 7:
            Insert_End();
            break;
        case 8:
            display_last();
            break;
           dafault:
            printf("Invalid choice");

        }
    }
return 0;}

void Insert_first()
{
    node *N=(node*)malloc(sizeof(node));
    printf("Enter the number:");
    scanf(" %d",&N->a);
    N->next=NULL;
    N->prev=NULL;
    if(head==NULL)
    {
        head=N;
        tail=N;
    }
    else
    {
        head->prev=N;
        N->next=head;
        head=N;

    }
}
void insert_any()
{
    int p;
    node *list=head;
    node *N=(node*)malloc(sizeof(node));
    printf("Enter the number:");
    scanf(" %d",&N->a);
    N->next=NULL;
    N->prev=NULL;
    printf("Enter Position: ");
    scanf(" %d",&p);
    if(p==1 )
    {
        if(head==NULL)
        {
            head=N;
            tail=N;
        }
        else
        {
            head->prev=N;
            N->next=head;
            head=N;
        }
    }
    else
    {
        p=p-2;
        while(p!=0 && list->next!=NULL)
        {
            list=list->next;
            p--;
        }
        if(list->next==NULL)
        {
            N->prev=tail;
            tail->next=N;
            tail=N;

        }
        else
        {
            list->next->prev=N;
            N->next=list->next;
            N->prev=list;
            list->next=N;
        }
    }


}
void Insert_End()
{
    node *N=(node*)malloc(sizeof(node));
    printf("enter the number:");
    scanf(" %d",&N->a);
    N->next=NULL;
    N->prev=NULL;
    node *list=head;
    if(head==NULL)
    {
        head=N;
        tail=N;
    }
    else
    {
        tail->next=N;
        N->prev=tail;
        tail=N;
    }

}



void  delete_data()
{
    int d;
    printf("Enter the number:");
    scanf(" %d",&d);
    node*list=head;
    if(head==NULL)
    {
        printf("No Data!!\n\n");
    }
    else if(list->a==d)
    {
        if(list->next==NULL)
        {
            head=NULL;
            tail=NULL;
            printf("Data Deleted\n\n");
            free(list);
        }
        else
        {
            list->next->prev=NULL;
            head=list->next;
            printf("Data Deleted\n\n");
            free(list);
        }
    }
    else
    {
        node*temp;
        while(list->a!=d && list->next!=NULL)
        {
            list=list->next;
            if(list==NULL)
            {
                printf("No Data Found!!\n\n");
                break;
            }
        }
        if(list->a==d && list->next==NULL)
        {
            list=tail;
            temp=list;
            temp->prev->next=temp->next;
            tail=temp->prev;
            printf("Data Deleted\n\n");
            free(temp);

        }
        else if(list->a==d && list->next!=NULL)
        {
            temp=list;
            temp->prev->next=temp->next;
            temp->next->prev=temp->prev;
            temp->next=NULL;
            temp->prev=NULL;
            printf("Data Deleted\n\n");
            free(temp);
        }

    }

}
void Delete_Position()
{

    int p;
    node *list=head,*temp;
    printf("Enter Position:");
    scanf(" %d",&p);
    if(head==NULL)
    {
        printf("No Position!!\n\n");
    }
    else if(p==1)
    {
        if(list->next==NULL)
        {
            printf("Data Deleted\n\n");
            free(list);
        }
        else
        {
            head=list->next;
            head->prev=NULL;
            printf("Data Deleted\n\n");
            free(list);
        }
    }
    else
    {
        p=p-2;
        while(p!=0 && list->next!=NULL)
        {
            list=list->next;
            p--;
            if(list==NULL)
            {
                printf("No Data Found!!\n\n");
                break;
            }
        }
        if(list->next==NULL)
        {
            printf("Wrong Position!!\n\n");
        }
        else if(list->next->next==NULL && p==0)
        {
            temp=tail;
            tail=tail->prev;
            tail->next=NULL;
            printf("Data Deleted\n\n");
            free(temp);
        }
        else if(list->next->next!=NULL && p==0)
        {
            temp=list->next;
            temp->next->prev=list;
            list->next=temp->next;
            printf("Data Deleted\n\n");
            free(temp);
        }
    }

}

void Search_Data()
{
    node *list=head;
    int s;
    printf("Enter Your number:");
    scanf("%d",&s);
    if(list->a==s)
    {
        printf("Found: %d\n\n",list->a);
    }
    else
    {
        while(list->a!=s)
        {
            list=list->next;
            if(list==NULL)
            {
                printf("No Data!!\n\n");
                break;
            }
        }
        printf("%d\n\n",list->a);
    }
}

void display_last()
{
    node*list=tail;
    if(head==NULL)
    {
        printf("No Data Available!!\n\n");


    }
    else
    {
        while(list!=NULL)
        {

            printf("%d\n\n",list->a);
            list=list->prev;
        }
    }

}
void display_first()
{
    node*list=head;
    if(head==NULL)
    {
        printf("No Data Available\n");


    }
    else
    {
        while(list!=NULL)
        {
            printf("%d\n",list->a);
            list=list->next;
        }
    }
    }