using System;

​

public class Program

{

    public static void Main()

    {

        Console.Write("Enter your marks: ");

        int marks = Convert.ToInt32(Console.ReadLine());

​

        string grade;

​

        if (marks >= 94 && marks <= 100)

            grade = "A+";

        else if (marks >= 87 && marks <= 93)

            grade = "A";

        else if (marks >= 80 && marks <= 86)

            grade = "A-";

        else if (marks >= 77 && marks <= 79)

            grade = "B+";

        else if (marks >= 73 && marks <= 76)

            grade = "B";

        else if (marks >= 70 && marks <= 72)

            grade = "B-";

        else if (marks >= 67 && marks <= 69)

            grade = "C+";

        else if (marks >= 63 && marks <= 66)

            grade = "C";

        else if (marks >= 60 && marks <= 62)

            grade = "C-";

        else if (marks >= 50 && marks <= 59)

            grade = "D";

        else if (marks >= 0 && marks <= 49)

            grade = "F";

        else

        {

            Console.WriteLine("Invalid input. Make sure that marks should be between 0 and 100.");

            return;

        }

​

        Console.WriteLine("Your grade is: " + grade);

    }

}

​