static void e13()
        {
            Random someRand = new Random();
            int s1, s2, count = 0;
            for (int i = 1; i <= 500; i++)
            {
                s1 = someRand.Next(6, 10);
                s2 = someRand.Next(6, 10);
                if ((s1 + s2) % 2 == 0)
                {
                    count++;
                }
            }
            Console.WriteLine(count);
        }
static void e16()
        {
            Console.WriteLine("Choose number");
            int num = int.Parse(Console.ReadLine());
            int multi = num % 10;
            while (num != 0)
            {

                num = num/ 10;
                if (num == 0)
                {
                    break;
                }
                multi = multi * (num % 10);
            }
            Console.WriteLine(multi);
        }