#include <iostream>
#include <vector>

int main()
{
    const std::size_t MAX_NUMBERS_ALLOWED = 6 ;
    std::vector<int> list_of_numbers ;

    std::cout << "enter up to " << MAX_NUMBERS_ALLOWED << " numbers\n" ;
    int number ;
    while( list_of_numbers.size() < MAX_NUMBERS_ALLOWED &&
           std::cout << "? " &&
           std::cin >> number )
    {
        list_of_numbers.push_back(number) ;
    }

    std::cout << "\nyou entered " << list_of_numbers.size() << " numbers: [ " ;
    for( int n : list_of_numbers ) std::cout << n << ' ' ;
    std::cout << "]\n" ;
}