public static int TheSecondMax()
  {
      List<int> myList = new List<int>() { 10, 20, 8, 20, 9, 5, 20, 10 };
      int max = int.MinValue;
      int secondMax = int.MinValue;
      foreach (var item in myList)
      {
          if (item > max)
          {
              max = item;
          }

          if (item > secondMax && item < max)
          {
              secondMax = item;
          }
      }

      return secondMax;
  }