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