#ifndef GRADE_H
#define GRADE_H
#include <iostream> //for classes istream and ostream
#include <string>   //for class string
using namespace std;

class grade {
private:
	int i;   //in the range 0 to n-1 inclusive; 0 means F, 13 means A+

	static const size_t n {14}; //the number of possible grades
	static const string a[n];   //names of the grades: "F", "F+", ..., "A+"
public:
	grade(): i {0} {}   //Default constructor puts F into newborn object.
	grade(const string& s);

	grade& operator+=(int inc);
	grade& operator-=(int inc);
	operator int() const {return i;}

	friend ostream& operator<<(ostream& ost, const grade& g) {
		return ost << grade::a[g.i];
	}
	friend bool operator==(const grade& g1, const grade& g2) {return g1.i == g2.i;}
	friend bool operator< (const grade& g1, const grade& g2) {return g1.i <  g2.i;}

	friend istream& operator>>(istream& ist, grade& g);
};
inline const grade  operator+(grade g,int n) {return g += n;}
inline const grade  operator+(int n, grade  g) {return g += n;}
inline const grade  operator-(grade g,int n) {return g -= n;}

inline grade& operator--(grade& g) {return g -= 1;}
inline grade& operator++(grade& g) {return g += 1;}
inline const grade operator++(grade& g, int)
{
	const grade old {g};
	++g;
	return old;
}

inline const grade operator--(grade& g, int)
{
	const grade old {g};
	--g;
	return old;
}	

inline bool operator> (const grade& g1, const grade& g2) {return g2 < g1;}
inline bool operator<=(const grade& g1, const grade& g2) {return !(g1 > g2);}
inline bool operator>=(const grade& g1, const grade& g2) {return g2 <= g1;}
inline bool operator!=(const grade& g1, const grade& g2) {return !(g1 == g2);}

#endif