Self describing numbers

/*
imagine making an explanation/description of a number my counting the amount of each digit in the number
like for example 111123.
the description of this number would be four 1's, one 2, and one 3.
however, you write down this description as a number
4 1's, 1 2, 1 3. 411213.

the goal of this program is to discover numbers where the description of (a number) is the same as the number itself
some examples are:
22
23322110
14333110
*/

using System;
using System.Collections;

namespace Self_Describing_Numbers
{
    class Program
    {
        static void Main(string[] args)
        {
            ArrayList NumbersArray = new ArrayList();

            for (int input = 0; input < 100000000; input++)
            {
                //optimization #2 (skip any input where every 2nd digit is smaller than the last)
                for (int i = 1; i < input.ToString().Length - 1; i += 2)
                {
                    int left = int.Parse(input.ToString()[i].ToString());
                    int right = int.Parse(input.ToString()[i + 2].ToString());

                    int toAdd = ((left - right) + 1) * (int)Math.Pow(10, input.ToString().Length - (i + 1));

                    if (toAdd > 0)
                    {
                        toAdd -= int.Parse(input.ToString().Substring(i + 3));
                        input += toAdd;
                        break;
                    }
                }

                //optimization #1 (skip any input number with odd amount of digits)
                if (input.ToString().Length % 2 != 0)
                {
                    input *= 10;
                }

                String outputString = "";

                int[] counts = new int[10];

                for (int i = 0; i < input.ToString().Length; i++)//go through every digit of the input number
                {
                    for (int j = 0; j < 10; j++)//go through all decimal digits
                    {
                        if (input.ToString()[i].ToString() == j.ToString())
                        {
                            counts[j]++;
                        }
                    }
                }

                for (int j = 0; j < 10; j++)
                {
                    if (counts[j] == 0)
                        continue;
                    outputString += counts[j];
                    outputString += j;
                }
                if (input.ToString() == outputString)
                {
                    NumbersArray.Add(input.ToString());
                    Console.WriteLine(input.ToString());
                }
            }

            Console.WriteLine("Found numbers:");
            foreach (Object obj in NumbersArray)
                Console.Write("{0}\n", obj);
        }
    }
}