#include <iostream>
using namespace std;

int main ()
{
	long int studentNum;
	double termMark;
	int count=12;
	int infinite=1;
	char letterGrade;
	cout << "Hello, Welcome to Student Information System Version 1. Please enter -1 if you want to exit the program"<<endl;
	while (infinite<count)
	{
	do
	{
		cout << "Please enter your 9 digit student number: ";
		cin >> studentNum;

		if (studentNum==-1)
		{
			cout << "Thank you";
			return 0;
		}
	} while( (studentNum<100000000) || (studentNum>999999999));

	do
	{
		cout << "Enter your grade (your grade must be between 0 and 100): ";
		cin >> termMark;
	} while (termMark<0 || termMark>100);

	if (termMark >85.5)
	{
		letterGrade = 'A';
	}
	else
	{
		if (termMark>73.5)
		{
			letterGrade= 'B';
		}
		else
		{
			if (termMark>61.5)
			{
				letterGrade= 'C';
			}
			else
			{
				if(termMark>49.5)
				{
					letterGrade= 'D';
				}
				else
				{
					letterGrade= 'F';
				}
			}
		}
	}

	cout.setf(ios::fixed);
	cout.setf(ios::showpoint);
	cout.precision(2);
	cout << "Student Number: " << studentNum << ", percentage grade: " << termMark << "." << endl;
	cout << "This student will recieve a"; if(letterGrade =='A'){cout<<"n ";} else {cout<<" ";} cout << letterGrade << "."<< endl;
	}

}