#include<iostream>
#include<string>
using namespace std;
class student {
    public:
    string name,subject;
    int marks;
    student (string n,string s,int m){
        name=n;
        subject=s;
        marks=m;
    }
    void displaygrade(){
        if(marks<0||marks>100||name==""||subject==""){
            cout<<"Invalid input"<<endl;
        }
        else{
            string grade;
            if(marks>=90)grade="A";
            else if(marks>=75)grade="B";
            else if(marks>=50)grade="C";
            else grade ="F";
            cout<<"Name: "<<name<<endl;
            cout<<"Subject: "<<subject<<endl;
            cout<<"Marks: "<<marks<<endl;
            cout<<"Grade: "<<grade<<endl;
        }
    }
};
int main(){
    string n,s;
    int m;
    if(! getline(cin,n))return 0;
    if(! getline(cin,s))return 0;
    if(!(cin>>m)return 0;
    student st(n,s,m);
    st.displaygrade();
    return 0;
}