using System;
public class Type2
{

    public static void main(String[] args)
    {

        double a, b, x, dx;
        
 
        a = 0.5;
        b = 4.5;
        dx = 0.4;
        while (true)
        {
            int s;
            Console.WriteLine("Choose an action: \n" +
                    "1 - Calculate using a loop with a premise \n" +
                    "2 - Calculate using a loop with a postcondition \n" +
                    "3 - Exit the program \n" +
                    "Your answer: ");
            string choose = Console.ReadLine();

            double y = 0;
            if (choose == "1")
            {
                x = a;
                Console.WriteLine("|  x      |   y=f(x)  |\n");
                while (x <= b)
                {
                    Console.WriteLine("|%.3f    |    %.2f   |\n", x, y);
                    x += dx;
                    y = Math.log(x);
                }
            }
            if (choose == "2")
            {
                x = a;
                Console.WriteLine("|  x      |   y=f(x)  |\n");
                do
                {
                    Console.WriteLine("|%.3f    |    %.2f   |\n", x, y);
                    x += dx;
                    y = Math.log(x);
                } while (x <= b);
            }
            if (choose == "3")
            {
                break;
            }
            else if (choose < 1 || choose > 3)
            {
                continue;
            }


        }
    }
}