using System;

public class Program

{

    public static void Main()

    {

            bool isNumber=false;

            string number1text="";

            string number2text="";

            while(!isNumber) 

            {

            Console.WriteLine("zadej cislo");

            number1text = Console.ReadLine();

            double numbers;

            bool isNumber1 = double.TryParse(number1text, out numbers);

            Console.WriteLine("zadej druhe cislo");

            number2text = Console.ReadLine();

            bool isNumber2= double.TryParse(number2text, out numbers);

            isNumber = isNumber1 && isNumber2;

            if (!isNumber)

                    Console.WriteLine("Spatny format, zadej cisla znovu");

​

            }

            double number1 = double.Parse(number1text);

            double number2 = double.Parse(number2text);

            double result = 0;

            if (isNumber)

            {

                Console.WriteLine("zadej matematickou operaci (+, - , *, / ) ");

                string operationText = Console.ReadLine();

                if (operationText == "+" || operationText == "plus")

​

                {

                    result = number1 + number2;

                }

                else if (operationText == "-" || operationText == "mínus")

​

                {

                    result = number1 - number2;

                }

                else if (operationText == "*" || operationText == "krát")

                {

                    result = number1 * number2;

                }

                else if (operationText == "/" || operationText == "dělěno")

                {

                    result = number1 / number2;

                }

​

                Console.WriteLine("Výsledek je " + result);

                Console.ReadLine();

            }

    }

}