class Node:

    def __init__(self, value):

        self.value = value

        self.next = None

​

class Stack:

    def __init__(self):

        self.head = None

        self.size = 0

    def push(self, value):

        new_node = Node(value)

        if self.head:

            new_node.next = self.head

        self.head = new_node

        self.size += 1

    def pop(self):

        if self.isEmpty():

            return "Stack is empty"

        popped_node = self.head

        self.head = self.head.next

        self.size -= 1

        return popped_node.value

    def peek(self):

        if self.isEmpty():

            return "Stack is empty"

        return self.head.value

    def isEmpty(self):

        return self.size == 0

    def stackSize(self):

        return self.size

​

# Usage

myStack = Stack()

myStack.push('A')

myStack.push('B')

myStack.push('C')

​

print("Pop: ", myStack.pop())

print("Peek: ", myStack.peek())

print("isEmpty: ", myStack.isEmpty())

print("Size: ", myStack.stackSize())

​

#Python

#include <stdio.h>

#include <stdlib.h>

​

struct Node {

    char value;

    struct Node *next;

};

​

struct Stack {

    struct Node *head;

    int size;

};

​

struct Stack *createStack() {

    struct Stack *s = malloc(sizeof(struct Stack));

    s->head = NULL;

    s->size = 0;

    return s;

}

​

void push(struct Stack *s, char value) {

    struct Node *newNode = malloc(sizeof(struct Node));

    newNode->value = value;

    newNode->next = s->head;

    s->head = newNode;

    s->size++;

}

​

char pop(struct Stack *s) {

    if (s->size == 0) {

        return ' ';

    }

    struct Node *popped = s->head;

    s->head = s->head->next;

    char poppedValue = popped->value;

    free(popped);

    s->size--;

    return poppedValue;

}

​

char peek(struct Stack *s) {

    if (s->size == 0) {

        return ' ';

    }

    return s->head->value;

}

​

int isEmpty(struct Stack *s) {

    return s->size == 0;

}

​

int stackSize(struct Stack *s) {

public class Main {

    public static void main(String[] args) {

        Stack myStack = new Stack();

        myStack.push('A');

        myStack.push('B');

        myStack.push('C');

​

        System.out.println("Pop: " + myStack.pop());

        System.out.println("Peek: " + myStack.peek());

        System.out.println("isEmpty: " + myStack.isEmpty());

        System.out.println("Size: " + myStack.size());

    }

}

​

class Node {

    char value;

    Node next;

    Node(char value) {

        this.value = value;

        this.next = null;

    }

}

​

class Stack {

    private Node head;

    private int size;

​

    public Stack() {

        this.head = null;

        this.size = 0;

    }

​

    public void push(char value) {

        Node newNode = new Node(value);

        if (head != null) {

            newNode.next = head;

        }

        head = newNode;

        size++;

    }

​

    public char pop() {

        if (isEmpty()) {

            return ' ';

        }

        char popped = head.value;

        head = head.next;

        size--;

        return popped;

    }

​