include

using namespace std; int main(){

int s;
s==(0^100);
cin>>s;
if(s==90||s==91||s==92||s==93||s==94||s==95||s==96||s==97||s==98||s==99||s==100){cout<<"A";}
if(s==80||s==81||s==82||s==83||s==84||s==85||s==86||s==87||s==88||s==89){cout<<"B";}
if(s==70||s==71||s==72||s==73||s==74||s==75||s==76||s==77||s==78||s==79){cout<<"C";}
if(s==60||s==61||s==62||s==63||s==64||s==65||s==66||s==67||s==68||s==69){cout<<"D";}
if(s==0||s==1||s==2||s==3||s==4||s==5||s==6){cout<<"E";}
if(s==50){cout<<"E";}
return 0;

}