#include <iostream>
using namespace std;

int main()
{
   int grade;

   cout << "Enter test grade: ";
   cin >> grade;

   cout << "The student's letter grade is: ";

   if (grade >= 90)
	cout << 'A';
   else if (grade >= 80)
	cout << 'B';
   else if (grade >= 70)
	cout << 'C';
   else if (grade >= 60)
	cout << 'D';
   else
	cout << 'F';

   cout << '\n';

   return 0;
}