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

Example Input: Titanium is found in column _ along with chemically similar zirconium, hafnium, and thorium.
Example Output: four

Example Input: Ice jams cause flooding because of _ main features.
Example Output: two

Example Input: Female manatees deliver only one calf every three to _ years.
Example Output:
five