DS Lab 5-Stack with Linked List

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

int count()
{
    struct node *temp;
    temp = head;
    int c=0;
    while(temp != NULL)
    {
        c++;
        temp = temp->next;
    }
    return c;
}

void display()
{
    struct node *temp;
    temp = head;
    if(temp == NULL)
        printf("List is empty\n");
    else
    {
        while(temp != NULL)
        {
            printf("%d ", temp->data);
            temp = temp->next;
        }
        printf("\n");
    }
}

void push(int num)
{
    struct node *temp;
    temp=(struct node*)malloc(sizeof(struct node));

    temp->data=num;

    if(head==NULL){
        head=temp;
        temp->next=NULL;
    }
    else{
        temp->next=head;
        head=temp;
    }
}


void delete()
{
    struct node *temp;
    temp = head;
    head = temp->next;
    free(temp);
    printf("Delete successful\n");
}
int main()
{
    int n, op, x;
    struct node *temp;
    while(1)
    {
        printf("\n1.Insert\n");
        printf("2.Display\n");
        printf("3.Size\n");
        printf("4.Delete\n");
        printf("5.Exit\n");
        printf("Enter your choice: ");
        scanf("%d", &op);
        if(op == 1)
        {
            printf("Enter number to insert: ");
            scanf("%d", &n);
            push(n);
        }
        else if(op == 2)
        {
            printf("Element(s) in the list are: ");
            display();
        }
        else if(op == 3)
        {
            printf("Size of the list is: %d", count());
        }
        else if(op == 4)
        {
            if(head == NULL)
                printf("List is empty!\n");
            else
            {
                delete();
            }
        }
        else if(op == 5)
            break;
        else
            printf("Invalid option\n");
    }
    return 0;
}