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

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

Ex Output:
no

Ex Input:
Plants have many white flowers with _ petals, giving the plant a white, flat-topped appearance.

Ex Output:
four

Ex Input:
All orchids have _ names.

Ex Output:
two