#include<bits/stdc++.h> using namespace std; int main (){ int a; cin>>a; if(a >= 90){ cout<<"A"; }else if(a < 90 && a>=80){ cout<<"B"; }else if(a < 80 && a>=70){ cout<<"C"; }else if(a < 70 && a>=60){ cout<<"D"; }else if(a < 60){ cout<<"E"; } return 0; }