# include<iostream> # include<cstdio> # include<iomanip> # include<cmath> using namespace std; int main(){ int a; cin>>a; a=a/10; switch(a) { case 10: case 9: cout<<'A'; break; case 7: case 8: cout<<'B'; break; case 6: cout<<'C'; break; default: cout<<'D';break; } return 0; }