getting lowest and greatet common factors

Hi,

I think that this is an errata, but I want to check this with you guyz.

I have a method called HasComFactor() method to get the lowest and greatest common factors if they exist.
The original code is in the below.  
However, I have a problem with
int max = x < y ? x : y;

I think that it should be
int max = x < y ? y : x;

For 3 and 21,
it cannot find the lcf and gcf with 'int max = x < y ? x : y;', so I think that this is an error.

Am I right?

class MyClass{
    public bool HasComFactor(int x, int y, out int lcf, out int gcf)
    {
        int max = x < y ? x : y;
        bool first = true;

        lcf = 1;
        gcf = 1;

        // Find lcf and gcf
        for (int i = 2; i < max/2 + 1; i++)
        {
            if(((y%i)==0) & ((x%i)==0))
            {
                if(first)
                {
                    lcf = i;
                    first = false;
                }
                gcf = i;
            }
        }// for
        if(lcf !=1)
            return true;
        else
            return false;
    }
}// MyClass

class demo{    
    static void Main()
    {
        MyClass ob = new MyClass();

        int lcf, gcf;
        if(ob.HasComFactor(3, 21, out lcf, out gcf))
        {
            Console.WriteLine("LCF of 3 and 21 is " + lcf);
            Console.WriteLine("GCF of 3 and 21 is " + gcf);
        }
        else
            Console.WriteLine("No common factor for 231, 105");    
        Console.Read();
    }
}