I'm getting the error "Oops, try again. median([4, 5, 5, 4]) returned 5.0 instead of 4.5"

I don't understand why this is occurring it seems to me that everything should be fine and I should be getting the correct result.

```
def median(list):
list = sorted(list)
c = len(list)
if len(list) == 1:
m = list[0]
return m
elif len(list) % 2 == 0:
a = list[(c / 2) + 1]
b = list[(c / 2)]
y = (a + b) / (2.0)
return y
else:
x = list[len(list) / 2]
x = x + 1
x = round(x)
return x
```

Thanks in advance for any help