#include <vector>
#include <iostream>
class a {
    float x,y,z;
 public:
    a(float a, float b, float c) : x(a), y(b), z(c) {}
};
int main()
{
    std::vector<a> b;
    b.emplace_back(0, 0, 0);
    b.push_back(a(0, 0, 0));

    std::cout << "b contains " << b.size() << " elements\n";
}