//Write a program to implement Stack using Linked List
#include<stdio.h>
#include<stdlib.h>
typedef struct node {
 int data;
 struct node *link;
} NODE;
NODE *start = NULL, *top = NULL;
void push(int item) {
 NODE *ptr = (NODE *)malloc(sizeof(NODE));
 if (ptr == NULL) {
 printf("\nMemory allocation failed.\n");
 exit(1);
 }
 ptr->data = item;
 ptr->link = top;
 top = ptr;
}
void pop() {
 if (top == NULL) {
 printf("\nStack is empty.\n");
 return;
 }
 NODE *s = top;
 printf("\nDeleted Element is %d\n", top->data);
 top = top->link;
 free(s);
 if (top == NULL) {
 start = NULL;
 }
}
void display() {
 if (top == NULL) {
 printf("\nStack is empty.\n");
 return;
 }
 printf("\nStack elements are:");
 NODE *display = top;
 while (display != NULL) {
 printf("\n%d", display->data);
 display = display->link;
 }
 printf("\n");
}
int main() {
 int no, item;
 char c;
 printf("\n\tPROGRAM TO INSERT, DELETE AND DISPLAY ELEMENTS TO STACK USING LINKED LIST");
 printf("\n\t.......................................................\n");
 do {
 printf("\t\t\t\tMENU\n");
 printf("\t\t1. INSERT\n\t\t2. DELETE\n\t\t3. DISPLAY\n\t\t4. EXIT\n\t\tEnter your choice: ");
 scanf("%d", &no);
 switch (no) {
 case 1:
 printf("\nEnter the element: ");
 scanf("%d", &item);
 push(item);
 break;
 case 2:
 pop();
 break;
 case 3:
 display();
 break;
 case 4:
 exit(0);
 default:
 printf("\nInvalid choice. Please enter a valid option.\n");
 }
 printf("\nDo you want to continue (y/n): ");
 scanf(" %c", &c);
 } while (c == 'y' || c == 'Y');
 return 0;
}