#include<iostream> using namespace std; int main(){ int M,A,B,C,D,E; cin>>M; if(90<=M&&M<=100) cout<<"A"; else if(80<=M&&M<90) cout<<"B"; else if(70<=M&&M<80) cout<<"C"; else if(60<=M&&M<70) cout<<"D"; else if(M<60) cout<<"E"; }