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

Example Input: All insects have _ body sections, the head , thorax , and abdomen.
Example Output: three

Example Input: Infertility affects one in _ couples and affects both men and women.
Example Output: seven

Example Input: Sexual maturity occurs at three to four years for females and _ to five years for males.
Example Output:
four