#ifndef POLYGON_H
#define POLYGON_H

#include <iostream>
#include <stdexcept>
#include <vector>
  
class Polygon
{
public:
  // Only one of the constructors required!
  Polygon(std::initializer_list<int> l);
  Polygon(int a, int b);

  Polygon& operator+=(int rhs);
  Polygon operator+(int rhs) const;
  
  double circumference() const;
  std::ostream& print(std::ostream& os) const;
  
private:
  int max_side() const;

  void validate() const;
  
  std::vector<int> sides;
};

Polygon operator+(int lhs, Polygon const& rhs);
std::ostream& operator<<(std::ostream& os, Polygon const& rhs);

#endif