#include<iostream>
#include<string>
#include<limits>
using namespace std; 
int main(){
    string name ,subject;
    int marks;
    if(!(cin >> name >> subject >> marks)){
        cout << "Invalid input" <<endl;
        return 0;
    }
    if(marks < 0 || marks > 100 || name.empty() || subject.empty()){
        cout << "Invalid input" <<endl;
    }else{
     char 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;
    }
    return 0;
}