import java.util.*;

public class Grade {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter marks:");
        int marks = sc.nextInt();

        if (marks >= 90 && marks < 100)
            System.out.println("Grade: S");
        else if (marks >= 80 && marks < 90)
            System.out.println("Grade: A");
        else
            System.out.println("Grade: B");
    }
}