#include <iostream>
#include <iomanip>
using namespace std;
char Convert (float);
int main()
{
	string first, last;
	int score;
	int stu_sum = 0;
	int stu_num_score = 0;
	float avg;
	char letter;
	cout << fixed << showpoint << setprecision(1);
	cin >> first;
	while(cin)
	{
		cin >> last;

		cout << first << " " << last << " ";
		cin >> score;

		while(score != -1)
		{
			stu_num_score ++;
			stu_sum += score;
			cin >> score;
		}
		avg = float(stu_sum)/stu_num_score;
		cout << avg << "\t";
		letter = Convert (avg);
		cout << letter << "\t";
		cout << " " << first << " " << last << " ";
		cout << "\n";
		cin >> first;
	}

	return 0;
}
char Convert (float score)   
{
        char letter;
        if (score>=90)
                letter = 'A';
        else if (score>=80)
                letter = 'B';
        else if (score>=70)
                letter = 'C';
        else if (score>=60)
                letter = 'D';
        else
                letter = 'F';
	return letter;
}