#include<iostream>
using namespace std;
class Result{
    public:
    int m,s,e,a;
    void get(int x,int y,int z,int w){m=x;s=y;e=z;a=w;}
    void show(){
        if(m<0||m>100||s<0||s>100||e<0||e>100||a<0||a>100){cout<<"Invalid input";return;}
        int t=m+s+e+a;
        cout<<t<<" "<<(t>=250?'A':t>200?'B':t>=150?'C':'F');
    }
};
int main(){
    int  m,s,e,a;cin>>m>>s>>e>>a;;
    Result r;r.get(mm,s,e,a);r.show();
}