class program
{
    static void Main(string[] args)
    {
        List<string> numbers = new List<string>();
        string[] arrayOne = { "1", "2", "1" };
        string[] arrayTwo = { "3", "2" };

        AddList(arrayOne, numbers);
        AddList(arrayTwo, numbers);

        foreach(var number in numbers)
        {
            Console.WriteLine(number);
        }
    }

    static void AddList(string[] array, List<string> list)
    {
        for (int i = 0; i < array.Length; i++)
        {
            if (list.Contains(array[i]) == false)
            {
                list.Add(array[i]);
            }
        }
    }
}