#include<iostream> // cin\cout\endl using namespace std; int main(){ int z; cin>>z; switch(z/10){ case 10: cout<<"A"<<endl;break; case 9: cout<<"A"<<endl;break; case 8: cout<<"B"<<endl;break; case 7: cout<<"B"<<endl;break; case 6: cout<<"C"<<endl;break; cout<<"D"<<endl; } return 0; }