#include "iostream"
#include "iterator"
#include "list"
using namespace std;

struct list_
{
    double x;
    list_ *prev, *next;
};

class tlist
{
public:
    list <double> list__;
    list <double> :: iterator pos_i_, pos_i, pos_N_i;
    tlist(int N)
    {
        double buf = 1;
        for (int i = 0; i < N; ++i)
        {
            std::cout << "������� x_" << i + 1 << " : ";
            std::cin >> buf;
            list__.push_back(buf);
        }

        pos_i = list__.begin();
        pos_N_i = list__.end();

    }
    double GetFromBegin(int i)
    {
        pos_i = list__.begin();
        advance(pos_i, i);
        int A = *pos_i;
        return A;
    }
    double GetFromEnd(int i)
    {
        pos_N_i = list__.end();
        advance(pos_N_i, -i);
        int A = *pos_N_i;
        return A;
    }
    ~tlist()
    {
        list__.erase(list__.begin() , list__.end());
        //cout << "! ! !   ����������   ! ! !" << endl;
    }

};