#include<iostream>
#include<string>

using namespace std;
class Student
{
public:
string name;
string subjects;
int marks;
public:
void displaygrade()
{
    if(name.empty() || subjects.empty() || marks<0 || marks>100 )
    {
        cout<<"Invalid input";
        return;
    }
char grade;
if(marks>=90)
{
    grade='A';
    
}
else if(marks>=75)
{
    grade='B';
}
else if(marks>=50)
{
    grade='C';
}
else
{
  grade='D';  
}
cout<<"Name: "<<name<<endl;
cout<<"Subject: "<<subject<<endl;
cout<<"Marks: "<<marks<<endl;
cout<<"Grade: "<<grade<<endl;


}
};
int main()
{
    Students s;
    getline(cin,s.name);
    getline(cin,s.subjects);
    cin>>s.marks;
    s.displaygrade();
    return 0;
    
}