----------------------------------------#2
#include <iostream>
#include <string>
#include <stack>

int main()
{
    std::stack<int> stack;
    std::string s;
    int el, i, count = 0;
    char curr;
    std::cin >> s;

    int size = s.size();

    for (i = 0; i < size; ++i) {


stack.push()
stack.empty()
stack.top()
stack.pop()
std::cout << "CORRECT";


------------------------------------#4
#include <iostream>
#include <deque>

int main()
{
    std::cin >> n;
    int A[n];
    char query;
    std::deque<int> deq;

    for (int i = 0; i < n; ++i)
        std::cin >> A[i];

    std::cin >> k;
    deq.push_back(A[0]);

deq.pop_back();
deq.push_back();
deq.pop_front()