include<bits/stdc++.h>

using namespace std ; int main(){

char grade; cin>>grade; switch(grade) {

case'A': cout<<"Very good!\n";break;
case'B': cout<<"Good!\n";break;
case'C': cout<<"OK!\n";break;
case'D': cout<<"Bad!\n";break;
default: cout<<"Too bad!\n";

}

return 0;

}