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