#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; if(n>=0&&n<=100) switch(n/10){ case 10: case 9:printf("A");break; case 8: case 7:printf("B");break; case 6:printf("C");break; case 5: case 4: case 3: case 2: case 1: case 0:printf("D");break; } return 0; }