include<bits/stdc++.h>

using namespace std ;

int main(){

int grade ;

cin >> grade ;

switch (grade)

{

case 5 :cout << "A" << endl; break ;

case 4 :cout << "B" << endl; break ;

case 3 :cout << "C" << endl; break ;

case 2 :cout << "D" << endl; break ;

case 1 :cout << "E" << endl;

}

return 0;

}