08. Letters Change Numbers

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

namespace LettersChangeNumb
{
    class LettersChangeN
    {
        public static decimal IterationthroughWords(char[] currentword)
        {
            decimal currentOperationsFirst = 0;
            for (int i = 0; i < currentword.Length; i++)
            {
                char beforeLetter = currentword.First();
                char afterLetter = currentword.Last();
                decimal number = ParseStringToInt(currentword);

                if (char.IsUpper(beforeLetter)) // Before -> Upper -> Divide
                {
                    decimal beforeLetterPosition = LowerOrUpperCasePositioning(beforeLetter); //Позиция на 1-а буква в азбуката,при главна буква
                    currentOperationsFirst = number / beforeLetterPosition;
                    number = currentOperationsFirst;

                }
                else if (char.IsLower(beforeLetter)) // Before -> Lower -> Multiply
                {
                    decimal beforePosition = LowerOrUpperCasePositioning(beforeLetter); //Позиция на 1-а буква в азбуката,при малка буква
                    currentOperationsFirst = number * beforePosition;
                    number = currentOperationsFirst;
                }
                if (char.IsUpper(afterLetter)) // After -> Upper -> Substract
                {
                    decimal afterPosition = LowerOrUpperCasePositioning(afterLetter); //Позиция на 2-а буква в азбуката,при главна буква
                    currentOperationsFirst = number - afterPosition;
                    number = currentOperationsFirst;
                }
                else if (char.IsLower(afterLetter)) // After -> Lower -> Add
                {
                    decimal afterPostion = LowerOrUpperCasePositioning(afterLetter); //Позиция на 2-а буква в азбуката,при малка буква
                    currentOperationsFirst = number + afterPostion;
                    number = currentOperationsFirst;
                }
            }
            return currentOperationsFirst;
        }
        public static decimal LowerOrUpperCasePositioning(char letter)
        {
            decimal indexOfLetter = 0;
            if (char.IsLower(letter))
            {
                string alphabet = "abcdefghijklmnopqrstuvwxyz";
                indexOfLetter = (alphabet.IndexOf(letter)) + 1;
            }
            else if (char.IsUpper(letter))
            {
                string alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
                indexOfLetter = (alphabet.IndexOf(letter)) + 1;
            }
            return indexOfLetter;
        }
        public static decimal ParseStringToInt(char[] letters)
        {

            String s = new string(letters);
            var removeFirst = s.Remove(0, 1);
            var removeLast = removeFirst.Remove(removeFirst.Length - 1, 1);
            decimal number = decimal.Parse(removeLast);

            return number;
        }
        static void Main(string[] args)
        {
            string[] input = Console.ReadLine().Split(new char[] { ' ' }, StringSplitOptions.RemoveEmptyEntries);
            decimal totalSumFirstChar = 0;

            if (input.Length >= 1 || input.Length <= 10)
            {
                for (int i = 0; i < input.Length; i++)
                {
                    char[] word = input[i].ToArray();
                    totalSumFirstChar += IterationthroughWords(word);
                }
                Console.WriteLine("{0:F2}", totalSumFirstChar);
            }
        }
    }
}