Оценки : Grades ; Loops

using System;

namespace tESt
{
    class Program
    {
        static void Main(string[] args)

        {
            var studentsNumber = double.Parse(Console.ReadLine());  //  students number

            double scoreTop = 0;      // Top
            double scoreGood = 0;     // Good
            double scoreMidle = 0;    // Middle
            double scoreFail = 0;     // Fail

            double allStudents = 0;

            double topStudents = 0;      // Top    numbers
            double goodStudents = 0;     // Good   numbers
            double midleStudents = 0;    // Middle numbers
            double failStudents = 0;     // Fail   numbers


            for (int i = 0; i < studentsNumber; i++)
            {
                var num = double.Parse(Console.ReadLine());

                allStudents = allStudents + 1;


                if (num >= 5.00)        // Top
                {
                    scoreTop = scoreTop + num;
                    topStudents = topStudents + 1;
                }
                else if (num >= 4.00)   // Good
                {
                    scoreGood = scoreGood + num;
                    goodStudents = goodStudents + 1;
                }
                else if (num >= 3.00)   // Middle
                {
                    scoreMidle = scoreMidle + num;
                    midleStudents = midleStudents + 1;
                }
                else if (num < 3.00)    // Fail
                {
                    scoreFail = scoreFail + num;
                    failStudents = failStudents + 1;
                }
            }

            var topPorcent = (topStudents / allStudents) * 100.0;     // Top    % (Porcentage)
            var goodPorcent = (goodStudents / allStudents) * 100.0;   // Good   % (Porcentage)
            var midlePorcent = (midleStudents / allStudents) * 100.0; // Middle % (Porcentage)
            var failPorcent = (failStudents / allStudents) * 100.0;   // Fail   % (Porcentage)

            var ScrowAll = (scoreTop + scoreGood + scoreMidle + scoreFail) / allStudents;

            Console.WriteLine($"Top students: {topPorcent:f2}%");
            Console.WriteLine($"Between 4.00 and 4.99: {goodPorcent:f2}%");
            Console.WriteLine($"Between 3.00 and 3.99: {midlePorcent:f2}%");
            Console.WriteLine($"Fail: {failPorcent:f2}%");

            Console.WriteLine( $"Average: {ScrowAll:f2}");
        }
    }
}