НОД

 public static void Nod()
        {
            int firstNumber = int.Parse(Console.ReadLine());
            int secondNumber = int.Parse(Console.ReadLine());
            int max = Math.Max(firstNumber, secondNumber);
            int min = Math.Min(firstNumber, secondNumber);
            int a = max;
            int b = min;
            int q = (int)Math.Floor((decimal)a / b);
            int r = a - b * q;
            int nod = r;
            while (r != 0)
            {
                a = b;
                b = r;
                q = (int)Math.Floor((decimal)a / b);
                nod = r;
                r = a - b * q;
            }
            Console.WriteLine(nod);
        }