int[] balls = new int[12];
            for (int i = 0; i < 12; i++)
                balls[i] = 4;
            Console.WriteLine("Please neter abnormal balls number: ");
            int num = Convert.ToInt32(Console.ReadLine()) - 1;
            balls[num] = 5;

            var set = from ball in balls
                      where ball == 5
                      select ball;

            foreach (int i in set)
                Console.WriteLine(i.ToString());