#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int a,n; cin>>a; n=a/10; switch(n) { case 10: case 9: cout<<"A"<<endl; break; case 7: case 8: cout<<"B"<<endl; break; case 6: cout<<"C"<<endl; break; default: cout<<"D"; break; } return 0; }