#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; if(a>=90) { cout<<'A'<<endl; } else if(a>=80) { cout<<'B'<<endl; } else if(a>=70) { cout<<'C'<<endl; } else if(a>=60) { cout<<'D'<<endl; } else { cout<<'E'<<endl; } return 0; }