#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)      // 3. fun definition
{       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;
}