#include<stdio.h>
#include<conio.h>
#include<stdlib.h>
#include<ctype.h>

struct node
{
	int info;
	struct node *next;
}*tos,*fresh,*ptr,*temp;
struct node *create()
{
	ptr=(struct node *)malloc(sizeof(struct node));
	printf("\n Enter value");
	scanf("%d",&ptr->info);
	ptr->next=NULL;
	return(ptr);
}
void push()
{
	char c;
	if(tos==NULL)
	{
		printf("\n Empty Stack");
		printf("\n Do you want to create the first node(Y/N)");
		if(toupper(getche())=='Y');
		{
			tos=create();
		}

	}
	else
	{
		fresh=create();
		fresh->next=tos;
		tos=fresh;
	}
}

void pop()
{
	if(tos==NULL)
		printf("\n Nothing to delete! Stack does not exist");
	else if(tos->next==NULL)
		{
			temp=tos;
			printf("\n Deleted element is %d",temp->info);
			tos=NULL;
			free(temp);
		}
	else
	{
		temp=tos;
		printf("\n Deleted value is %d",temp->info);
		tos=tos->next;
		free(temp);
	}
}
void display()
{
	ptr=tos;
	if(tos==NULL)
		printf("\n Nothing to display");
	else
	{
		while(ptr!=NULL)
		{
			printf("\n %d",ptr->info);
			ptr=ptr->next;
		}
	}
}
void main()
{
	int ch;
	char choice='Y';
	tos=NULL;
	clrscr();
	printf("1. PUSH");
	printf("\n2. POP");
	printf("\n3. DISPLAY");
	printf("\n4. Exit");
	while(choice=='Y')
	{
		printf("\n Enter your choice(1/2/3/4)");
		scanf("%d",&ch);
		switch(ch)
		{
			case 1: push();
				display();
				break;
			case 2: pop();
				display();
				break;
			case 3: display();
				break;
			case 4: exit(1);
			default: printf("\n Invalid choice");
		}
		printf("\n Enter your choice to continue");
		choice=toupper(getche());
	}
	getch();
}