def median(lst):
    """
    Return a list's median
    :param lst:     List (sorted or not) of int
    :return:        int
    """
    lst.sort()
    length = len(lst)

    if length == 0:
        return None
    elif length % 2 == 0:
        # Even number of elements
        return (lst[int((length+1)/2 - 1)] + lst[int((length+1)/2)]) / 2.0
    else:
        return lst[int((length+1)/2 - 1)]