def median(lst):
  if type(lst)==list:
    lst=sorted(lst)
    count=len(lst)
    if count%2==0:
        index_1 = len(lst)/2 - 1
        index_2 = len(lst)/2
        #left=lst[count/2 - 1]
        #right=lst[count/2]
        return (lst[index_1] + lst[index_2])/2.0
    else:
        index = len(lst)//2
        return lst[index]


print (median([2, 4, 5, 9]))