namespace ConsoleApp3
{
    struct Gr
    {
        public struct Student
        {
            public string fam;
            public double[] rez;
            public double sred;
            public int gr;
            public Student(string fam, int gr, double[] rez)
            {
                sred = 0;
                this.fam = fam;
                this.rez = rez;
                this.gr = gr;
                for (int i = 0; i < 5; i++)
                    sred += rez[i];
                sred /= 5;
            }
        }

    }

    class Program
    {
        static void Main(string[] args)
        {
            double sred1 = 0;
            double sred2 = 0;
            double sred3 = 0;
            int kol1 = 0;
            int kol2 = 0;
            int kol3 = 0;

            Gr.Student[] cl = new Gr.Student[15];
            cl[0] = new Gr.Student("Иванов", 1, new double[] { 3, 4, 5, 5, 5 });
            cl[1] = new Gr.Student("Верба", 1, new double[] { 3, 2, 3, 5, 4 });
            cl[2] = new Gr.Student("Эйснер", 1, new double[] { 4, 4, 5, 5, 3 });
            cl[3] = new Gr.Student("Гутник", 1, new double[] { 3, 4, 5, 2, 3 });
            cl[4] = new Gr.Student("Косяков", 1, new double[] { 0, 1, 1, 1, 1 });
            cl[5] = new Gr.Student("Рыбалко", 2, new double[] { 5, 5, 5, 5, 5 });
            cl[6] = new Gr.Student("Бердникова", 2, new double[] { 4, 4, 4, 5, 4 });
            cl[7] = new Gr.Student("Банан", 2, new double[] { 4, 4, 5, 4, 3 });
            cl[8] = new Gr.Student("Груша", 2, new double[] { 5, 4, 5, 4, 4 });
            cl[9] = new Gr.Student("Яблоко", 2, new double[] { 4, 5, 5, 5, 3 });
            cl[10] = new Gr.Student("Синий", 3, new double[] { 4, 4, 5, 5, 5 });
            cl[11] = new Gr.Student("Красный", 3, new double[] { 4, 4, 4, 4, 4 });
            cl[12] = new Gr.Student("Черный", 3, new double[] { 4, 4, 5, 5, 4 });
            cl[13] = new Gr.Student("Белый", 3, new double[] { 3, 4, 5, 2, 2 });
            cl[14] = new Gr.Student("Зеленый", 3, new double[] { 3, 5, 5, 5, 4 });

            Gr.Student[] students1 = new Gr.Student[5];
            Gr.Student[] students2 = new Gr.Student[5];
            Gr.Student[] students3 = new Gr.Student[5];

            for (int i = 0; i < cl.Length; i++)
            {
                switch(cl[i].gr)
                {
                    case (1):
                        students1[kol1] = cl[i];
                        sred1 += cl[i].sred;
                        kol1++;
                        break;
                    case (2):
                        students2[kol2] = cl[i];
                        sred2 += cl[i].sred;
                        kol2++;
                        break;
                    case (3):
                        students3[kol3] = cl[i];
                        sred3 += cl[i].sred;
                        kol3++;
                        break;
                }
            }
            sred1 /= kol1;
            sred2 /= kol2;
            sred3 /= kol3; // na kol!

            List<double> sred = new List<double>();
            sred.Add(sred1); sred.Add(sred2); sred.Add(sred3);
            sred.Sort();
            sred.Reverse();

            for (int i = 0; i < 3; i++)
            {
                if (sred[i] == sred1)
                {
                    Console.WriteLine($"Группа 1 {sred1}");
                    Console.WriteLine();
                    for (int ii = 0; ii < students1.Length; ii++)
                        Console.WriteLine($"{students1[ii].fam} {students1[ii].sred}");
                    Console.WriteLine();
                }
                else if (sred[i] == sred2)
                {
                    Console.WriteLine($"Группа 2 {sred2}");
                    Console.WriteLine();
                    for (int ii = 0; ii < students2.Length; ii++)
                        Console.WriteLine($"{students2[ii].fam} {students2[ii].sred}");
                    Console.WriteLine();
                }
                else if (sred[i] == sred3)
                {
                    Console.WriteLine($"Группа 3 {sred3}");
                    Console.WriteLine();
                    for (int ii = 0; ii < students3.Length; ii++)
                        Console.WriteLine($"{students3[ii].fam} {students3[ii].sred}");
                    Console.WriteLine();
                }
            }
            Console.Read();
        }
    }
}