#include <iostream>
#include <vector>

using Stack = std::vector<int>;

void push(Stack &s, int v) {
    s.push_back(v);
}

void pop(Stack &s) {
    s.pop_back();
}

int top(Stack const &s) {
    return s[s.size() - 1];
}

bool is_empty(Stack const &s) {
    return s.size() == 0;
}

int main(int, char const *[]) {
    Stack my_stack;
    for (int i = 0; i < 4; ++i) {
        push(my_stack, i);
    }
    std::cout << "Topo atual " << top(my_stack) << std::endl;
    pop(my_stack);
    for (int i = 0; i < 3; ++i) {
        push(my_stack, 3*i);
    }

    std::cout << "Pilha atual: ";
    while ( !is_empty(my_stack) ) {
        auto x = top(my_stack);
        pop(my_stack);
        std::cout << x << " ";
    }
    std::cout << std::endl;
}