Wektor w definicji klasy

#include <SFML/Graphics.hpp>
#include <cmath>
#include <iostream>
#include <cstdlib>


class solver
{
    double ilosc;
   
public:
   
    void initialize( double total_disks )
    {
        total_disks = ilosc;
    }
   
private:
    std::vector < sf::RectangleShape > pierwszy( ilosc );
    std::vector < sf::RectangleShape > drugi( ilosc );
    std::vector < sf::RectangleShape > trzeci( ilosc );
   
};

int main() {
    double liczba = 10;
    solver Solver;
    Solver.initialize( liczba );
   
    return 0;
}