Hi guys, I have some problem with this exercise and the following is my code:

```
def median(lista):
lista.sort()
lun = len(lista)
if lun % 2 == 0 and lun != 0:
a = lista[(lun / 2)]
b = lista[((lun / 2) + 1)]
c = float
c = round (a + b) / 2
return c
elif lun == 1:
return lista[0]
else:
return lista[(lun / 2) + 1]
```

And this is the error I get:

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

I think It is a matter of approximation but I don't know precisely how to fix it...can anyone please help me?

Thank you