write c# program to read student mark between 0 to 100, then prints the equal grade

using System.Runtime.Intrinsics.X86;

internal class Program
{
    private static void Main(string[] args)
    {
        int mark;
        Console.Write("enter your mark: ");
        mark = Convert.ToInt32(Console.ReadLine());
        if (mark >= 90 && mark <= 100)
            Console.WriteLine("A");
        else if (mark >= 80 && mark < 89)
            Console.WriteLine("B");
        else if (mark >= 70 && mark < 79)
            Console.WriteLine("C");
        else if (mark >= 60 && mark < 69)
            Console.WriteLine("D");
        else if (mark >= 0 && mark < 60)
            Console.WriteLine("Fail");
    }
}