#include<bits/stdc++.h> using namespace std; int main(){ double a; cin>>a; if(a<10.0)cout<<'A'; else if(a>=10.0 and a<20.0)cout<<"B"; else if(a>=20.0 and a<40.0)cout<<'C'; else if(a>=40.0 and a<50.0)cout<<"D"; else cout<<'E'; }