using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public abstract class SchoolMembers

    {

        public string name;

        public string egn;

        public string dateofbirth;

        public string phonenum;

        public string input;

    }

    public class Grade

    {

        private string subject;

        private double mark;

        private string date;

        public string Subject { get; set; }

        public double Mark { get; set; }

        public string Date { get; set; }

        public Grade(string subject, double mark, string date)

        {

            this.Subject = subject;

            this.Mark = mark;

            this.Date = date;

        }

    }

    public class Student : SchoolMembers

    {

        private string klass;

        private string subject;

        private double grade;

        public string Klass{ get; set; }

        public string Subject { get; set; }

        public double Grade { get; set; }

        public List<Grade> grades = new List<Grade>();

        public Student(string name, string egn, string dateofbirth, string phonenum) : base() {}

        private void NewStudent()

        {

            var input = Console.ReadLine().Split(' ').ToList();

            Student student = new Student(input[0], input[1], input[2], input[3]);

        }

        public void InputGrade()

        {

            Console.Write("Enter student = ");

            this.name = Console.ReadLine();

            while (true)

            {

                Console.Write("Would you like to enter a new grade?(y/n) - ");

                string input = Console.ReadLine().ToLower();

                if (input == "y")

                {

                    Console.Write("Please enter the subject, the mark (2 - 6), and the date: ");

                    var grad = Console.ReadLine().Split(' ').ToList();

                    Grade grade = new Grade(grad[0], int.Parse(grad[1]), grad[2]);

                }

            else if (input == "n") { break; }

            }

        }

        public void OutputGrades(List<Grade> grades)

        {

            foreach(Grade grade in grades)

            Console.WriteLine("Subject = {0}, Grades = {1}.", this.subject, this.grade);

        }

    }

    public class Square : SchoolMembers

    {

        static int sq = 0; public int num;

        private double a;

        private double areaQ;

        public string name;

        public double A { get; set; }

        public Square() { sq++; this.num = sq; this.name = "Square " + num;}

        public override void Input()

        {

            Console.Write("Writing for square:\nSide A = ");

            this.a = double.Parse(Console.ReadLine());

        }

        public override void Output()

        {

            Console.WriteLine("Side A = {0}", this.a);

        }

        public override double Area()

        {

            this.AreaQ = (this.a) * (this.a);       return AreaQ;

        }

                public override void WriteDown()

        {

            Console.WriteLine("Figure {0} area = {1:F2} cm2.", this.name, this.AreaQ);

        }

    }

​

    public class Rectangle : Figure

    {

        static int re = 0; public int num;

        private double a;

        private double b;

        private double areaQ;

        public string name;

​

        public double A { get; set; }

        public double B { get; set; }

        public Rectangle() { re++; this.num = re; this.name = "Rectangle " + num;}

​

        public override void Input()

        {

            Console.Write("Writing for triangle:\nSide A = ");

            this.a = double.Parse(Console.ReadLine());

​

            Console.Write("Side B = ");

            this.b = double.Parse(Console.ReadLine());

        }

        public override void Output()

        {

            Console.WriteLine("Side A = {0}, Side B = {1}", this.a, this.b);

        }

        public override double Area()

        {

            this.AreaQ = (this.a) * (this.b);       return AreaQ;

        }

                        public override void WriteDown()

        {

            Console.WriteLine("Figure {0} area = {1:F2} cm2.", this.name, this.AreaQ);

        }

    }

    public class Circle : Figure

    {

        static int ci = 0; public int num;

        private double r;

        private double areaQ;

        public string name;

​

        public double R { get; set; }

        public Circle() { ci++; this.num = ci; this.name = "Circle " + num;}

​

        public override void Input()

        {

            Console.Write("Writing for circle:\nRadius = ");

            this.r = double.Parse(Console.ReadLine());

        }

        public override void Output()

        {

            Console.WriteLine("Radius = {0}", this.r);

        }

        public override double Area()

        {

            this.AreaQ = (this.r) * (this.r) * Math.PI;     return AreaQ;

        }

                        public override void WriteDown()

        {

            Console.WriteLine("Figure {0} area = {1:F2} cm2.", this.name, this.AreaQ);

        }

    }

​

    public class Trapezoid : Figure

    {

        static int trap = 0; public int num;

        private double a;

        private double b;

        private double h;

        private double areaQ;

        public string name;

​

        public double A { get; set; }

        public double B { get; set; }

        public double H { get; set; }

        public Trapezoid() { trap++; this.num = trap; this.name = "Trapezoid " + num;}

​

        public override void Input()

        {

            Console.Write("Writing for trapezoid:\nBase 1 = ");

            this.a = double.Parse(Console.ReadLine());

​

            Console.Write("Base 2 = ");

            this.b = double.Parse(Console.ReadLine());

​

            Console.Write("Height = ");

            this.h = double.Parse(Console.ReadLine());

        }

        public override void Output()

        {

            Console.WriteLine("Base 1 = {0}, Base 2 = {1}, Height = {2}", this.a, this.b, this.h);

        }

​

        public override double Area()

        {

            this.AreaQ = ((this.a) + (this.b)) * (this.h) / 2;      return AreaQ;

        }

                        public override void WriteDown()

        {

            Console.WriteLine("Figure {0} area = {1:F2} cm2.", this.name, this.AreaQ);

        }

    }

    public static void Main()

    {

        List<Figure> figures = new List<Figure>();

​

        while (true)

        {

            Console.Write("Would you like to enter a new shape?(y/n) - ");

            string input = Console.ReadLine().ToLower();

            if (input == "y")

            {

                Console.Write("Please write a number (1 - Triangle, 2 - Square, 3 - Circle, 4 - Trapezoid): ");

                int num = int.Parse(Console.ReadLine());

                if (num == 1)

                {

                    Triangle triangle = new Triangle();

                    triangle.Input(); triangle.Output(); Console.WriteLine("Area equals {0:F2} cm2.", triangle.Area());

                    figures.Add(triangle);

                }

                else if (num == 2)

                {

                    Square square = new Square();

                    square.Input(); square.Output(); Console.WriteLine("Area equals {0:F2} cm2.", square.Area());

                    figures.Add(square);

                }

                else if (num == 3)

                {

                    Circle circle = new Circle();

                    circle.Input(); circle.Output(); Console.WriteLine("Area equals {0:F2} cm2.", circle.Area());

                    figures.Add(circle);

                }

                else if (num == 4)

                {

                    Trapezoid trapezoid = new Trapezoid();

                    trapezoid.Input(); trapezoid.Output(); Console.WriteLine("Area equals {0:F2} cm2.", trapezoid.Area());

                    figures.Add(trapezoid);

                }

​

                else

                    throw new ArgumentException("Write a number between 1 and 4.");

            }

            else if (input == "n")

            {

                break;

            }

            else

                throw new ArgumentException("Please write y or n.");

        }

        foreach(var figure in figures.OrderBy(x => x.AreaQ))

        { figure.WriteDown(); }

    }

}

​

​

​

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