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