Question: i am doing this online course on udemy and everything works fine but when i try to intialize the first hidden layer it gave the following error 

```
TypeError: __init__() missing 1 required positional argument: 'units'.

```

then I did the ctrl+I on the spyder and chnged the output\_dim and init arguments but i dont know what to replace others with ..

```
import keras
from keras.models import Sequential
from keras.layers import Dense

#initializing the ANN
classifier = Sequential()

#adding the input layer and the first hidden layer
classifier.add(Dense(units =6, kernel_initializer = 'uniform' , activation = 'relu', input_dim =11 ))

#adding the second layer

classifier.add(Dense(Output_dim = 6 , kernel_initializer = 'uniform' , activation = 'relu'))

```

should work fine with no error

Answer: 
You can use window functions:

```
select subject
from (select subject, count(*) as cnt,
             max(count(*)) over () as max_cnt,
             min(count(*)) over () as min_cnt
      from t
      group by subject
     ) s
where cnt not in (max_cnt, min_cnt);

```
Another approach:

```
SELECT SUBJECT
FROM STUDENTS
GROUP BY SUBJECT
HAVING COUNT(*) > 1 AND COUNT(*) < 3

```