Preview:
class Program
{
    static void Main()
    {
        Console.WriteLine("Enter a number: ");
        int num = Convert.ToInt32(Console.ReadLine());
        if (IsPrime(num))
        {
            Console.WriteLine("Prime Number");
        }
        else
        {
            Console.WriteLine("Not a Prime Number");
        }
    }

    static Boolean IsPrime(int num)
    {
        if (num == 1 || num == 0) return false;
        int c = 0;
        for(int i = 1; i <= num; i++)
        {
            if(num%i == 0)
            {
                c++;
            }
        }

        return c == 2;
    }
}
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