#include <iostream>
using namespace std;
/* This is an initial comment.
Asher Stuhlman, June 28, 2006 */

int main() {
	int value;
	cout << "GRADE = ?" << endl;
	cin >> value;
	if (value < 60)
		cout << endl << "F!!" << endl;
	else
		{	
		value = value%100;
		value = value/10;
		value = -value+74;
		cout << char(value) << endl;
		} 
	return 0;
}

//Doesn't work with 100. Help?