---

#include <iostream>
#include <vector>

class IntVect {
public:
    static const int size0 = 16;
    int ar0[size0];
    int* arr[10] = { NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL };
    int size = 0;
    int reserve = 10;
    int& operator[](int index)
    {
        if (index < size0)
            return ar0[index];
        else
        {
            index >>= 4;
            int count = -1;
            int chunksize = 8;
            while (index > 0)
            {
                index >>= 1;
                count++;
                chunksize *= 2;
            }
            if (arr[count] == NULL)
            {
                arr[count] = new int[chunksize];
                return ar0[0];//todo
            }
            else
                return ar0[0];//todo

        }
    }
    //push_back(int)
};
int main()          {
    IntVect iv;
    iv[10] = 10;
    iv[20] = 20;
    iv[21] = 20;
    iv[35] = 20;
    iv[36] = 20;


    //std::vector<int> v{ 1, 2, 3, 4, 5 };
    ////v.capacity()
    ////v.push_back()
    //int first = v.front();    // 1
    //int last = v.back();      // 5
    //int second = v[1];        // 2
    //std::cout << "first: " << first << std::endl;
    //std::cout << "second: " << second << std::endl;
    //std::cout << "last: " << last << std::endl;

    //v[0] = 6;  // изменяем значение   
    //for (int n : v)
    //    std::cout << n << "\t"; // 6  2  3  4  5
    //std::cout << std::endl;
}