Exam 6. Five Special Letters

namespace _4.FiveSpecialLetters
{
    using System;

    public class FiveSpecialLetters
    {
        public static void Main(string[] args)
        {
            checked
            {
                long startNum = long.Parse(Console.ReadLine());
                long endNum = long.Parse(Console.ReadLine());

                bool foundRightSequence = false;
                for (char i = 'a'; i <= 'e'; i++)
                {
                    for (char j = 'a'; j <= 'e'; j++)
                    {
                        for (char k = 'a'; k <= 'e'; k++)
                        {
                            for (char m = 'a'; m <= 'e'; m++)
                            {
                                for (char n = 'a'; n <= 'e'; n++)
                                {
                                    string word = string.Empty  + i + j + k + m + n;
                                    long weightSeq = WeightOfSingleLetter(i);
                                    long index = 2;
                                    if (j != i)
                                    {
                                        weightSeq += WeightOfSingleLetter(j) * index;
                                        index++;
                                    }

                                    if (k != i && k != j)
                                    {
                                        weightSeq += WeightOfSingleLetter(k) * index;
                                        index++;
                                    }

                                    if (m != i && m != j && m != k)
                                    {
                                        weightSeq += WeightOfSingleLetter(m) * index;
                                        index++;
                                    }

                                    if (n != i && n != j && n != k && n != m)
                                    {
                                        weightSeq += WeightOfSingleLetter(n) * index;
                                    }

                                    if (weightSeq >= startNum && weightSeq <= endNum)
                                    {
                                        foundRightSequence = true;
                                        Console.Write("{0} ", word);
                                    }
                                }
                            }
                        }
                    }
                }

                if (!foundRightSequence)
                {
                    Console.WriteLine("No");
                }
            }
        }

        private static long WeightOfSingleLetter(char letter)
        {
            checked
            {
                long weight = 0;
                switch (letter)
                {
                    case 'a':
                        weight = 5;
                        break;
                    case 'b':
                        weight = -12;
                        break;
                    case 'c':
                        weight = 47;
                        break;
                    case 'd':
                        weight = 7;
                        break;
                    case 'e':
                        weight = -32;
                        break;
                }

                return weight;
            }
        }
    }
}