#include <iostream>
#include <cstring>

int main()
{
    using namespace std;

    const float ENGLISH_MIDTERM_PROCENTAGE = .25;
    const float ENGLISH_FINALTERM_PROCENTAGE = .25;
    const float ENGLISH_REASEARCH_PROCENTAGE = .30;
    const float ENGLISH_PRESENTATION_PROCENTAGE = .20;
    const float MATH_MIDTERM_PROCENTAGE = .50;
    const float MATH_FINALTERM_PROCENTAGE = .50;
    const float SCIENCE_MIDTERM_PROCENTAGE = .40;
    const float SCIENCE_FINALTERM_PROCENTAGE = .40;
    const float SCIENCE_REASEARCH_PROCENTAGE = .20;

    int midterm_grade = 0;
    int finalterm_grade = 0;
    int reasearch_grade = 0;
    int presentation_grade = 0;

    float Final_grade = 0;
    char final_letter_grade;
    char response[256];
    string grades_to_callculater;


    cout << "Do you want to callculate the grade ? : ";
    cin >> grades_to_callculater;

    for (int i = 0; i < grades_to_callculater.length();i++){
        grades_to_callculater[i] = toupper(grades_to_callculater[i]);
    }

    while(grades_to_callculater == "YES")
    {

    cout << "Enter student type " << "(1-English, 2-Math,3-Sience): ";
    cin.getline(response,256);

    if (strlen(response) == 0){
        cout << "Please enter valid number...";
        return 1;
    }
    if (atoi(response) < 1 | atoi(response) > 3){
        cout << "Please enter valid number...";
        return 1;
    }

    switch (atoi(response))
    {
    case 1:
        cout << "ENTER Midterm grade:";
        cin.getline(response,256);
        midterm_grade = atoi(response);
        cout << "ENTER Finalterm grade:";
        cin.getline(response,256);
        finalterm_grade = atoi(response);
        cout << "ENTER Research grade:";
        cin.getline(response,256);
        reasearch_grade = atoi(response);
        cout << "ENTER Presentation grade:";
        cin.getline(response,256);
        presentation_grade = atoi(response);

        Final_grade =
        (midterm_grade*ENGLISH_MIDTERM_PROCENTAGE)+
        (finalterm_grade*ENGLISH_FINALTERM_PROCENTAGE)+
        (reasearch_grade*ENGLISH_REASEARCH_PROCENTAGE)+
        (presentation_grade*ENGLISH_PRESENTATION_PROCENTAGE);
        if (Final_grade > 93)
            final_letter_grade = 'A';
        else
        if ((Final_grade >= 85) & (Final_grade < 93))
            final_letter_grade = 'B';
        else
        if ((Final_grade >= 78) & ( Final_grade < 85))
            final_letter_grade = 'C';
        else
        if ((Final_grade >= 70) & (Final_grade < 78))
            final_letter_grade = 'D';
        else
        if (Final_grade < 70)
            final_letter_grade = 'F';

        cout << "***ENGLISH STUDENT***" << endl << endl;
        cout << "Midterm grade is: " << midterm_grade << endl;
        cout << "Finalterm grade is : " << finalterm_grade << endl;
        cout << "Reasearch grade is : " << reasearch_grade << endl;
        cout << "Presentation grade is : " << presentation_grade << endl << endl;
        cout << "Final grade is :" << final_letter_grade;
        break;

    case 2:
        cout << "ENTER Midterm grade:";
        cin.getline(response,256);
        midterm_grade = atoi(response);
        cout << "ENTER Finalterm grade:";
        cin.getline(response,256);
        finalterm_grade = atoi(response);

        Final_grade =
        (midterm_grade*MATH_MIDTERM_PROCENTAGE)+
        (finalterm_grade*MATH_FINALTERM_PROCENTAGE);

        if (Final_grade > 90)
            final_letter_grade = 'A';
        else
        if ((Final_grade >= 83) &(Final_grade < 90))
            final_letter_grade = 'B';
        else
        if ((Final_grade >= 76) & (Final_grade < 83))
            final_letter_grade = 'C';
        else
        if ((Final_grade >= 65) & (Final_grade < 76))
            final_letter_grade = 'D';
        else
        if (Final_grade < 65)
            final_letter_grade = 'F';

        cout << "***MATH STUDENT***" << endl << endl;
        cout << "Midterm grade is: " << midterm_grade << endl;
        cout << "Finalterm grade is : " << finalterm_grade << endl << endl;
        cout << "Final grade is :" << final_letter_grade;
        break;

    case 3:
         cout << "ENTER Midterm grade:";
        cin.getline(response,256);
        midterm_grade = atoi(response);
        cout << "ENTER Finalterm grade:";
        cin.getline(response,256);
        finalterm_grade = atoi(response);
        cout << "ENTER Reasearch grade:";
        cin.getline(response,256);
        reasearch_grade = atoi(response);


        Final_grade =
        (midterm_grade*SCIENCE_MIDTERM_PROCENTAGE)+
        (finalterm_grade*SCIENCE_FINALTERM_PROCENTAGE)+
        (reasearch_grade*SCIENCE_REASEARCH_PROCENTAGE);

        if (Final_grade > 90)
            final_letter_grade = 'A';
        else
        if ((Final_grade >= 80) & (Final_grade < 90))
            final_letter_grade = 'B';
        else
        if ((Final_grade >= 70) & (Final_grade < 80))
            final_letter_grade = 'C';
        else
        if ((Final_grade >= 60) & (Final_grade < 70))
            final_letter_grade = 'D';
        else
        if (Final_grade < 60)
            final_letter_grade = 'F';
        cout << "***SCIENCE STUDENT***" << endl << endl;
        cout << "Midterm grade is: " << midterm_grade << endl;
        cout << "Finalterm grade is : " << finalterm_grade << endl;
        cout << "Reasearch grade is : " << reasearch_grade << endl << endl;
        cout << "Final grade is :" << final_letter_grade;
        break;
    default:
        cout << "- Is not valid student type.";
        return 1;
    }

    cout << endl << endl << "Do you have another grade to calcuclate? : ";
    cin >> grades_to_callculater;

    for (int i = 0; i < grades_to_callculater.length();i++){
        grades_to_callculater[i] = toupper(grades_to_callculater[i]);
    }

    }
    return 0;
}