#include <iostream>
#include <string>

using namespace std;

class Student{
    private:
    string name;
    string subject;
    int marks;
    
    public:
     Student(string n, string s, int m) : name(n), subject(s), marks(m){}
     
     void displayGrade(){
         if (marks < 0||marks > 100||name.empty() || subject.empty()){
             
         }
         else {
             char grade;
             if(mark < 0 || marks  > 100|| name.empty()|| subject.empty()){
                 
             }
             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;
                 
             }
         }
     }
     int main()
     Student s1("Alice", "Mathematics", 95);
     s1.displayGrade();
     
     return 0;}