#include<iostream> 
using namespace std;

void main()
{

	const int A_MULTIPLIER = 4;
	const int B_MULTIPLIER = 3;
	const int C_MULTIPLIER = 2;
	const int D_MULTIPLIER = 1;
	const int F_MULTIPLIER = 0;

	char grade;

	cout << "Grade? ";
	cin >> grade;

	//if(grade == 'A' || grade == 'a' || 
	//	grade == 'B' || grade == 'b' ||
	//	grade == 'C' || grade == 'c' ||
	//	grade == 'D' || grade == 'd' ||
	//	grade == 'F' || grade == 'f' )
	//{
	//	cout << "Valid grade" << endl;
	//}
	//else
	//{
	//	cout << "Invalid grade" << endl;
	//}

	/////////////////////////////////////////////////////////////
	//grade = toupper(grade);

	//if(grade == 'A' ||  
	//	grade == 'B' || 
	//	grade == 'C' || 
	//	grade == 'D' || 
	//	grade == 'F' )
	//{
	//	cout << "Valid grade" << endl;
	//}
	//else
	//{
	//	cout << "Invalid grade" << endl;
	//}

	/////////////////////////////////////////////////////////////

	do
	{
		cout << "Grade?";
		cin >> grade;
		grade = toupper(grade);
	}
	//while(!((grade >= 'A' && grade <= 'D') || grade == 'F' ));
	while(((grade < 'A' || grade > 'D') && grade != 'F' ));



	//if(!(x > 8 && y == 99 || z <= 34 && b))
	//if((x <= 8 || y != 99 && z > 34 || !b))


}