#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>  // for bool, true, false

#define MAX 5  // fixed size of the stack

// Stack structure
typedef struct {
    int data[MAX];
    int top;
} Stack;

// Function prototypes
void initialize(Stack *s);
bool isFull(Stack *s);
bool isEmpty(Stack *s);
void push(Stack *s, int value);
int pop(Stack *s);
int size(Stack *s);

// Initialize the stack
void initialize(Stack *s) {
    s->top = -1;
}

// Check if stack is full
bool isFull(Stack *s) {
    return s->top == MAX - 1;
}

// Check if stack is empty
bool isEmpty(Stack *s) {
    return s->top == -1;
}

// Push element onto stack
void push(Stack *s, int value) {
    if (isFull(s)) {
        printf("Stack overflow! Cannot push %d\n", value);
        return;
    }
    s->data[++(s->top)] = value;
    printf("Pushed %d\n", value);
}

// Pop element from stack
int pop(Stack *s) {
    if (isEmpty(s)) {
        printf("Stack underflow! Cannot pop.\n");
        return -1;  // return sentinel value
    }
    int poppedValue = s->data[(s->top)--];
    printf("Popped %d\n", poppedValue);
    return poppedValue;
}

// Return current size of stack
int size(Stack *s) {
    return s->top + 1;
}

// Main function to demonstrate stack operations
int main() {
    Stack s;
    initialize(&s);

    push(&s, 10);
    push(&s, 20);
    push(&s, 30);
    push(&s, 40);
    push(&s, 50);
    push(&s, 60); // overflow test

    printf("\nCurrent stack size: %d\n", size(&s));

    pop(&s);
    pop(&s);

    printf("\nAfter popping, stack size: %d\n", size(&s));

    if (isEmpty(&s))
        printf("Stack is empty.\n");
    else
        printf("Stack is not empty.\n");

    if (isFull(&s))
        printf("Stack is full.\n");
    else
        printf("Stack is not full.\n");

    return 0;
}