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

Input: Consider Input: Humans host _ species of louse, the head louse , the body louse and the pubic louse .

Output: three


Input: Consider Input: Planaria has rudimentary eyes which produce _ images but detect direction.

Output: no


Input: Consider Input: Gerbils usually live for three to _ years.


Output: four