#include<iostream>
using namespace std;
class Student{
    string n,s;int m;
public:
    Student(string n1,string s1,int m1){n=n1,s=s1,m=m1;}
    void displayGrade(){
        if(n==""||s==""||m<0||m>100){
            cout<<"Invalid input";
            return;
        }
        char g=(m>=90)?'A':(m>=75)?'B':(m>=50)?'C':'F';
        cout<<"Name:"<<n<<"\nSubject:"<<s<<"\nMarks:"<<m<<"\nGrade:"<<g;
    }
};
int main(){
    string n,s;int m;
    getline(cin,n);
    grtline(cin,s);
    cin>>m;
    Student(n,s,m).displayGrade();
}