//This test scoring program does not accept test scores
//that are less than 0 or greater than 100.
#include <iostream>
using namespace std;

int main ()
{
	//Constants for grade tresholds
	const int A_SCORE = 90,
			  B_SCORE = 80,
			  C_SCORE = 70,
			  D_SCORE = 60,
			  MIN_SCORE = 0,	//Minimum valid score
			  MAX_SCORE = 100;	//Maximum valid score
	
	int testScore;	//To hold a numeric test score
	
	//Get the numeric test score
	cout << "Enter your numeric test score and I will \n"
		 << "tell you the letter grade you earned: ";
	cin >> testScore;
	
	//Validate the input and determine the grade.
	if (testScore >= MIN_SCORE && testScore <= MAX_SCORE)
	{
		if (testScore >= A_SCORE)
			cout << "Your grade is A.\n";
		else if (testScore >= B_SCORE)
			cout << "Your grade is B.\n";
		else if (testScore >= C_SCORE)
			cout << "Your grade is C.\n";
		else if (testScore >= D_SCORE)
			cout << "Your grade is D.\n";
		else 
			cout << "Your grade is F.\n";
	}
	else 
	{
		//An invalid score was entered.
		cout << "That is an invalid score. Run the program\n"
			 << "again and enter a value in the range of\n"
			 << MIN_SCORE << " through " << MAX_SCORE << ".\n";
	
	return 0;
	}
}