Классы и средняя Perf групп

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApp11
{
    class Program
    {

        class Student
        {

             private string name;
             private string numbergroup; //Поля
             private int[] performance = new int[5];

            public Student(string name, string numbergroup, int[] performance)
            {
                this.name = name;
                this.numbergroup = numbergroup; // Конструктор
                this.performance = performance;
            }
            public Student()
            {

            }

            public Student(char var)
            {
                this.numbergroup = "ИДБ-19-11";
                this.name = "Василий";
                this.performance[0] = 5;
                this.performance[1] = 4;
                this.performance[2] = 3;
                this.performance[3] = 2;
                this.performance[4] = 3;
            }

            public Student(bool var)
            {
                this.numbergroup = "НВГУ-1859";
                this.name = "Алихан";
                this.performance[0] = 3;
                this.performance[1] = 4;
                this.performance[2] = 2;
                this.performance[3] = 4;
                this.performance[4] = 2;
            }

            public Student(float var)
            {
                this.numbergroup = "187-1";
                this.name = "Максим";
                this.performance[0] = 5;
                this.performance[1] = 5;
                this.performance[2] = 3;
                this.performance[3] = 3;
                this.performance[4] = 4;
            }

            public string Name
            {
                get
                {
                    return name;
                }
                set
                {
                    name = value;
                }
            }

            public string Numbergroup
            {
                get
                {
                    return numbergroup;
                }
                set
                {
                    numbergroup = value;
                }
            }
            public int[] Performance
            {
                get
                {
                    return performance;
                }
                set
                {
                    performance = value;
                }
            }

            public void Output()
            {
                Console.WriteLine(Name + " " + Numbergroup + " группа");
                for (int i = 0; i < Performance.Length; i++)
                {
                    Console.WriteLine(Performance[i]);
                }
            }


        }


        static int[] Input()
        {
            const int len = 5;
            int[] Performance = new int[len];
            for (int i = 0; i < Performance.Length; i++)
            {
                Console.WriteLine("Введите " + i + " оценку");
                Performance[i] = int.Parse(Console.ReadLine());

            }
            return Performance;
        }





        static void Main(string[] args)
        {
            List<Student> students = new List<Student>();
            int[] massive = new int[3] { 2, 3, 4 };
            int a = massive[2];
            students.Add(new Student('F'));
            students.Add(new Student(1));
            students.Add(new Student(true));
            // Student b = students[0];



            int n = 1;
            while (n != 0)
            {
                Console.WriteLine("===============================================================");
                Console.WriteLine("Введите номер команды: ");
                Console.WriteLine("1.Добавить студента");
                Console.WriteLine("2.Вывести информацию о студенте");
                Console.WriteLine("3.Удалить информацию о последнем студенте");
                Console.WriteLine("4.Удаление информации студента по индексу");
                Console.WriteLine("5.Вывести информацию по имени студента");
                Console.WriteLine("6.Вывести среднее значение по оценкам каждого студента");
                Console.WriteLine("0.Выйти из программы");
                Console.WriteLine("===============================================================");
                n = int.Parse(Console.ReadLine());
                switch (n)
                {
                    case 1:
                        Console.Clear();
                        Console.WriteLine("Введите имя");
                        string Name = Console.ReadLine();
                        Console.WriteLine("Введите номер группы");
                        string Numbergroup = Console.ReadLine();
                        Console.WriteLine("Введите 5 оценок");
                        int[] Performance = Input();

                        students.Add(new Student(Name, Numbergroup, Performance));
                        break;

                    case 2:
                        Console.Clear();
                        foreach (Student student in students)
                        {
                            student.Output();
                        }
                        break;

                    case 3:
                        Console.Clear();
                        students.RemoveAt(students.Count - 1);
                        break;

                    case 4:
                        Console.Clear();
                        Console.WriteLine("Введите индекс удаляемого студента");
                        int index = 0;
                        index = int.Parse(Console.ReadLine());
                        if (index > students.Count)
                        {
                            Console.WriteLine("Некорректный индекс");
                        }
                        else
                        {
                            students.RemoveAt(index);
                        }
                        break;
                    case 5:
                        Console.Clear();
                        string temp;
                        Console.WriteLine("Введите имя студента");
                        temp = Console.ReadLine();

                        bool flag = false;
                        foreach (Student student in students)       // foreach(1)тип 2)Название 3)in (Откуда берется список)
                        {
                            if (temp == student.Name)
                            {
                                student.Output();
                                flag = true;

                            }
                        }
                        if (flag == false)
                        {
                            Console.WriteLine("Такой студент не найден");
                        }
                        break;
                    case 6:
                        Console.Clear();
                        int summ;
                        foreach (Student student in students)
                        {
                            summ = 0;
                            for (int i = 0; i < student.Performance.Length; i++)
                            {

                                summ += student.Performance[i];
                            }

                            int average = summ / student.Performance.Length;
                            Console.WriteLine(average);
                        }
                        break;
                    case 7:
                        List<string> arr_name_group = new List<string>();
                        List<int> arr_count_numbergroup = new List<int>();
                        List<float> arr_sum_numbergroup = new List<float>();
                        for (int i = 0; i < students.Count; i++)
                        {
                            float sum = 0;
                            for (int j = 0; j < 5; j++)
                            {
                                sum += students[i].Performance[j];
                            }

                            bool flag1 = false;

                            for (int j = 0; j < arr_name_group.Count; j++)
                            {
                                if (arr_name_group[j] == students[i].Numbergroup)
                                {
                                    arr_count_numbergroup[j]++;
                                    arr_sum_numbergroup[j] += sum / 5;

                                    flag1 = true;
                                    break;
                                }
                            }
                            if (flag1 == false)
                            {
                                arr_name_group.Add(new string ('F',5));
                                arr_name_group[arr_name_group.Count - 1] = students[i].Numbergroup;
                                arr_count_numbergroup.Add(new int());
                                arr_count_numbergroup[arr_count_numbergroup.Count - 1] = 1;
                                arr_sum_numbergroup.Add(new float());
                                arr_sum_numbergroup[arr_sum_numbergroup.Count - 1] = sum / 5;
                            }
                        }
                        for (int i = 0; i < arr_name_group.Count; i++)
                        {
                            Console.WriteLine("Группа" + arr_name_group[i] + "Имеет средний балл");
                            Console.WriteLine(arr_sum_numbergroup[i] / arr_count_numbergroup[i]);
                        }
                        break;
                    case 0:
                        break;

                    default:
                        Console.WriteLine("Вы ввели неверное значение");
                        break;
                }
            }

        }
    }
}
//Student st = students[0];