```
def median(lst):
for i in range(len(lst)):
if len(lst)%2==0:
return (lst[int(len(lst)/2)-1]+lst[int(len(lst)/2)])/2.0
elif len(lst)==1:
return lst[i]
elif len(lst)%2!=0:
return lst[int(len(lst)/2)]
```

i really do not understand why i'm wrong

It is an error:

Oops, try again. median([4, 5, 5, 4]) returned 5.0 instead of 4.5

But median for this case is (5+5)/2=5