using System;
namespace ConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            string final = null;
            Console.WriteLine("Введите текст и нажмите Enter");
            string text = Console.ReadLine();
            foreach (char ch in text)
            {
                if (!Char.IsLetter(ch))
                    final += ch;
                else
                {
                    if (Char.IsLower(ch))
                        final += Char.ToUpper(ch);
                    else
                        final += Char.ToLower(ch);
                }
            }
            Console.WriteLine(final);
        }
    }
}