#include <iostream>
using namespace std;
class Student(){
    public:
    string name,subject;
    int mark;
    cin>>name>>subject;
    cin>>mark;
    void Student(string name,string subject,int mark){
        cout<<"Name: "<<name<<endl;
        cout<<"Subject: "<<subject<<endl;
        cout<<"Marks: "<<mark<<endl;
        if(mark<0 && mark>100){
            cout<<"Invalid input";
        }
        else if(mark>=90){
            cout<<"Grade: "<<"A";
        }
        else if(mark>=75 && mark<90){
            cout<<"Grade: "<<"B";
        }
        else if(mark>=50 && mark<75){
            cout<<"Grade: "<<"C";
        }
        else{
            cout<<"Grade: "<<"F";
        }
    }
};
int main(){
    Student m;
    m.Student();
    return 0;
}
}