include
using namespace std;
int main() {
int s ;
cin >> s;// 90 <= s <=100
if (90 <= s && s <= 100)
cout << 'A';
else if (80 <= s && s < 90)
cout << 'B';
else if (70 <= s && s < 80)
cout << 'C';
else if (60 <= s && s < 70)
cout << 'D';
else
cout << 'E';
return 0;
}