Prime number [C#]

using System;

using System.Collections.Generic;

using System.Text;
namespace primeorcomposite
{


    class prime_or_Composite
    {
        static void Main()
        {
            int a,cont=1;
            bool flag=true;
        get_input:
            flag = true;
            Console.Write("\n\nEnter any number: ");
            a = int.Parse(Console.ReadLine());

            for (int i = 2; i < a; i++)
            {
                if (a % i == 0)
                {
                    flag = false;
                    break;
                }
            }
            if (!flag)
            {
                Console.ForegroundColor = ConsoleColor.Red;
                Console.Beep(500, 500);
                Console.WriteLine("\n{0} is not a Prime Number!", a);
            }
            else
            {
                Console.ForegroundColor = ConsoleColor.Green;
                Console.Beep(1000, 500);
                Console.WriteLine("\n{0} is a Prime Number!", a);
            }
            Console.ForegroundColor = ConsoleColor.Gray;
            Console.WriteLine("\nContinue? < 1 or 0 >");
            cont = int.Parse(Console.ReadLine());
            if (cont == 1)
                goto get_input;
            else
            {
                Console.WriteLine("Thank You!\nExiting.......");
                Console.Beep(750, 300) ;
                Console.Beep(750, 300);
                Console.Beep(750, 300);
            }
        }

    }


}