inte

static void Main(string[] args)
        {
            int number = 5;
            string numberBinary = Convert.ToString(number, 2);
            var charArray = numberBinary.ToArray();
            for (int i = 0; i < numberBinary.Length; i++)
            {
                if (charArray[i] == '1')
                {
                    charArray[i] = '0';
                }
                else
                {
                    charArray[i] = '1';
                }
            }
            string complement = "";
            for (int i = 0; i < numberBinary.Length; i++)
            {
                complement += charArray[i];
            }
            int number11 = Convert.ToInt32(complement, 2);
            Console.WriteLine(number11);
            Console.ReadLine();
        }