программа с классом

#include <iostream>
 
class Sphere {
 public:
  Sphere() : id_(0), color_(0), radius_(0.0) {}
  Sphere(size_t id, int color, float radius)
    : id_(id), color_(color), radius_(radius) {}
  size_t Id() const { return id_; }
  int Color() const { return color_; }
  float Radius() const { return radius_; }
  void Id(size_t value) { id_ = value; }
  void Color(int value) { color_ = value; }
  void Radius(float value) { radius_ = value; }
  bool operator<(const Sphere &other) const {
    return radius_ < other.Radius();
  }
  friend std::ostream &operator<<(std::ostream &s, const Sphere &other) {
    return s << "ID: " << other.Id()
             << ", color: " << other.Color()
             << ", radius: " << std::fixed << other.Radius();
  }
 private:
  size_t id_;
  int color_;
  float radius_;
};
 
Sphere &Min(Sphere &a, Sphere &b) {
  return ((a < b) ? a : b);
}
 
int main(int argc,char *argv[]) {
  Sphere a(0, 200, 25.2), b(1, 200, 26.3), c(2, 300, 25.1);
  std::cout << a << std::endl << b << std::endl << c << std::endl;
  std::cout << "Min: " << Min(a, Min(b, c)) << std::endl;
  return 0;
}