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

Ex Input:
Men produce brand new sperm every _ to three months.

Ex Output:
two


Ex Input:
Water is able to diffuse freely between the _ cells.

Ex Output:
two


Ex Input:
Liposomes have _ main advantages over plain dry capsule or tablet delivery methods.

Ex Output:

three