04 Split by Word Casing

using System;
using System.Collections.Generic;
using System.Linq;

namespace _04_Split_By_Word_Casing
{
    class Program
    {
        static void Main(string[] args)
        {
            List<string> input = Console.ReadLine().Split(new char[]
            { ',', ';', ':', '.', '!', '(', ')', '"', '\\', '/', '[', ']', ' ' },
            StringSplitOptions.RemoveEmptyEntries).ToList();

            List<string> lowerCase = new List<string>();
            List<string> mixedCase = new List<string>();
            List<string> upperCase = new List<string>();

            foreach (string word in input)
            {
                int lowerCaseLetters = 0;
                int upperCaseLetters = 0;

                foreach (char letter in word)
                {
                    if (char.IsLower(letter))
                    {
                        lowerCaseLetters++;
                    }
                    else if (char.IsUpper(letter))
                    {
                        upperCaseLetters++;
                    }
                }

                if (lowerCaseLetters != word.Length && upperCaseLetters != word.Length)
                {
                    mixedCase.Add(word);
                }
                else if (lowerCaseLetters == word.Length)
                {
                    lowerCase.Add(word);
                }
                else
                {
                    upperCase.Add(word);
                }
            }
            Console.WriteLine("Lower-case: " + string.Join(", ", lowerCase));
            Console.WriteLine("Mixed-case: " + string.Join(", ", mixedCase));
            Console.WriteLine("Upper-case: " + string.Join(", ", upperCase));

        }
    }
}