using System;

using System.Collections.Generic;

using System.Linq;

using System.Net.Mime;

​

public class Program

{

    public static void Main()

    {

        var start = 246540;

        var stop = 787419;

        //var start = 111122;

        //var stop = 111122;

        var hits = 0;

​

        var current = start;

        while (current <= stop)

        {

            var s = current.ToString();

            current++;

​

            var chars = s.ToCharArray().ToList();

​

            chars.Sort();

            var orderedS = new string(chars.ToArray());

            if (orderedS != s)

            {

                continue;

            }

​

            var hasDouble = false;

            foreach (var c in chars)

            {

                if (hasDouble)

                {

                    break;

                }

​

                var pair = $"{c}{c}";

                var tripple = $"{c}{c}{c}";

                if(System.Text.RegularExpressions.Regex.Matches(s, pair).Count > 0 && System.Text.RegularExpressions.Regex.Matches(s, tripple).Count == 0)

                {

                    hasDouble = true;

                }

            }

            if (hasDouble)

            {

                hits++;

            }

        }

​

        Console.WriteLine(hits);

        //Console.ReadLine();

    }

}