using System;

public class Program

{

​

​

        private bool[] cisla;

​

        public Program(int n) 

        {

            this.cisla = new bool[n];

            cisla[0] = cisla[1] = true;

            for (int i = 2; i < Math.Sqrt(n); i++)

            {

                if (cisla[i] == true) continue;

                for (int j = 2 * i; j < n; j += i)

                    cisla[j] = true;

            }

        }

​

        public String toString()

        {

            String str = "";

            for (int i = 2; i < cisla.Length; i++)

            {

                if (cisla[i] == false)

                    {str += i + ", ";Console.WriteLine(str);}

            }

        }

    }

​

​