//他会吃符号要加#
include
int main() {
int score;
std::cin >> score;
char grade;
if (score >= 90) {
grade = 'A';
} else if (score >= 80) {
grade = 'B';
} else if (score >= 70) {
grade = 'C';
} else if (score >= 60) {
grade = 'D';
} else {
grade = 'E';
}
std::cout << grade << std::endl;
return 0;
}
