判断用书输入的是不是素数？（C#）

public static void main()

{

      int count;

      Console.WriteLine("请输入一个正整数");

      count=Convert.ToInt32(Console.ReadLine());

      for(int i=2;i<count;i++)

     {

            if（count % i ==0)

            {

                  Console.WriteLine("{0} is not sushu",count）; break;

            }

            else

            {

                  Console.WriteLine("{0} is sushu",count); break;

            }

     }

}