#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 10: case 9:cout<<"A";break; case 8: case 7:cout<<"B";break; case 6:cout<<"C";break; case 5: case 4: case 3: case 2: case 1:cout<<"D";break; } return 0; }