In this task, find the most appropriate number to replace the blank (indicated with _ ) and express it in words.

Ex Input:
Germs have _ means of locomotion execpt to attach themselves to particles of dust.

Ex Output:
no


Ex Input:
Pure water contains _ ions and is therefore a nonconductor .

Ex Output:
no


Ex Input:
Cubes symbolize the stability of the _ elements.

Ex Output:

four