Letters combination

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Exercise_6__Letters_Combi
{
    class Program
    {
        static void Main(string[] args)
        {

            // 23:50 -  00:10

            char firstLetter =  char.Parse(Console.ReadLine());
            char secondLetter = char.Parse(Console.ReadLine());
            char forbiddenLetter = char.Parse(Console.ReadLine());
            int cnt = 0;

            for (char i = firstLetter; i <= secondLetter; i++)
            {
                for (char k = firstLetter; k <= secondLetter; k++)
                {
                    for (char l = firstLetter; l <= secondLetter; l++)
                    {
                        if ( i != forbiddenLetter && k != forbiddenLetter && l != forbiddenLetter)
                        {
                            Console.Write($"{i}{k}{l} ");
                            cnt++;
                        }
                    }
                }
            }

            Console.WriteLine(cnt);



        }
    }
}