#include <iostream>
#include <string>

using namespace std;

int main(){

	//Variables
	string grade = "";
	double value = 0.0;
	bool valid = true;

	//Input
	cout << "Enter a grade: " << endl;
	cin >> grade;


	//Validation
	if (!(grade.substr(0, 1) == "A" || grade.substr(0, 1) == "B" || grade.substr(0, 1) == "C" || grade.substr(0, 1) == "D" || grade.substr(0, 1) == "F"))
	{
		valid = false;
	}

	else if (grade.length() > 2)
	{
		valid = false;
	}

	else if (grade.length() == 2)
	{
			if (grade.substr(1, 1) != "+" || grade.substr(1, 1) != "-")
			{
				valid = false;
				cout << "stuff" << endl;
			}
	}

	//Assigning value to grade
		if (valid == true){
			if (grade.substr(0, 1) == "A"){
				value = 4.0;
			}

			else if (grade.substr(0, 1) == "F"){
				value = 0.0;
			}

			else if (grade.substr(0, 1) == "B"){
				value = 3.0;
			}

			else if (grade.substr(0, 1) == "C"){
				value = 2.0;
			}

			else if (grade.substr(0, 1) == "D"){
				value = 1.0;
			}

			// + or -
			if (grade.substr(1, 1) == "+"){
				value += 0.3;
			}

			else if (grade.substr(1, 1) == "-"){
				value -= 0.3;
			}
		}

	//Output
	if (valid ==  false){

		cout << "Input is invalid." << endl;


	}
	else if (valid == true){
		cout << "Numeric value: " << value << endl;
	}

	//Other
	system("pause");
	return 0;
}