#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 n; cin>>n; n/=10; switch(n);{ case 10; case 9; cout<<"A"; break; case 7; case 8; cout<<"B"; break; case 6; cout<<"C"; break; default; cout<<"D"; } return 0; }