arrays

using System;

namespace Arrays
{
    class Program
    {
        static void Main(string[] args)
        {
            int[] a = new int[] { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
            int[] b = new int[] { 10, 11, 12 };

            int[] c = new int[Math.Max(a.Length, b.Length)];

            for (int index = 0; index < c.Length; index++)
            {
                int aValue = (a.Length > index) ? a[index] : b[index];
                int bValue = (b.Length > index) ? b[index] : a[index];

                c[index] = Math.Max(aValue, bValue);
            }

            //Console.WriteLine(String.Join(", ", c));
        }
    }
}