input: def read_array_and_find_mean_median(arr):
      """Read an array from the user and then determine the mean and median of the array.
      >>> read_array_and_find_mean_median([10, 15, 20, 25, 30, 35])
      (22.5, 22.5)
      """
output:     arr.sort()
      n = len(arr)
      mean = sum(arr) / n
      median = arr[n // 2] if n % 2 != 0 else (arr[n // 2 - 1] + arr[n // 2]) / 2
      return mean, median