using System;

​

class Program

{

    float[] Numbers = new float[5] {0, 0, 0, 0, 0};

    char Operator;

    string TempInput;

    public float CanConvert()

    {

        TempInput = Console.ReadLine();

        bool CanConvert = float.TryParse(TempInput, out Numbers[0]);

        if (CanConvert)

        {

        }

        else

        {

            if(TempInput == "Ans")

            {   

                Numbers[0] = Numbers[4];

            }

            else

            {

                Console.WriteLine("N/A");

            }

        }

        return Numbers[0];

    }

    public void Input()

    {

        Console.WriteLine("Please enter the first number");

        CanConvert();

        Numbers[1] = Numbers[0];

        Console.WriteLine("Please enter the second number");

        CanConvert();

        Numbers[2] = Numbers[0];

    }

    public void Output()

    {

        Console.WriteLine(Numbers[1] + " " + Operator + " " + Numbers[2] + " = " + Numbers[4]);

        Numbers[3] = Numbers[4];

    }

    static void Main(string[] args)

    {

        Program Calculator = new Program();

        while (true)

        {

            Console.WriteLine("Which mathemartical operator do you plan on using? \n1. Addition \n2. Subtraction \n3. Multiplication \n4. Division \nTo close the calculator enter 5");

            int choice = Convert.ToInt32(Console.ReadLine());

            switch (choice)

            {

                case 1:

                    Calculator.Input();

                    Calculator.Numbers[4] = Calculator.Numbers[1] + Calculator.Numbers[2];

                    Calculator.Operator = '+';

                    Calculator.Output();

                    break;

                case 2:

                    Calculator.Input();

                    Calculator.Numbers[4] = Calculator.Numbers[1] - Calculator.Numbers[2];

                    Calculator.Operator = '-';

                    Calculator.Output();

                    break;

                case 3:

                    Calculator.Input();

                    Calculator.Numbers[4] = Calculator.Numbers[1] * Calculator.Numbers[2];

                    Calculator.Operator = '*';

                    Calculator.Output();

                    break;

                case 4:

                    Calculator.Input();

                    Calculator.Numbers[4] = Calculator.Numbers[1] / Calculator.Numbers[2];

                    Calculator.Operator = '/';

                    Calculator.Output();

                    break;

                case 5:

                    return;

            }

        }

    }

}