ds - push,pop operation in stack (linked list implementation)

#include"stdio.h"
#include"conio.h"
#include"alloc.h"
#include"stdlib.h"
struct stack
{
int data;
int count;
struct stack *next;
};
typedef struct stack stack;
void push(stack **,int);
void pop(stack **);
void display(stack *);
void main()
{
stack *s=NULL;
clrscr();
s->count=0;
push(&s,5);
push(&s,10);
push(&s,15);
display(s);
pop(&s);
printf("\n");
display(s);
getch();
}
void push(stack **s,int d)
{
stack *newnode=(stack *)malloc(sizeof(stack));
if(newnode==NULL)
{printf("memory overflow");
exit(0);}
(*s)->count++;
newnode->data=d;
newnode->next=(*s);
(*s)=newnode;

}
void pop(stack **s)
{
stack *p;
if(*s==NULL)
{printf("underflow");
exit(0);}
p=*s;
(*s)->count--;
*s=(*s)->next;

free(p);
}
void display(stack *s)
{
while(s!=NULL)
{printf("%d ",s->data);
s=s->next;}
}