include

include

using namespace std; int main(void){

//froepen("1116.in","r",stdin);
//freopen("1116.out","w",stdout);
int s;
scanf("%d",&s);
if(s<=100&&s>=90) printf("A");
if(s<90&&s>=80) printf("B");
if(s<80&&s>=70) printf("C");
if(s<70&&s>=60) printf("D");
if(s<60&&s>=0) printf("E");
return 0;

}