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

Ex Input:
Seasons occur because of _ factors working together.

Ex Output:
two

Ex Input:
Coho usually live for _ years and grow rapidly in their final year.

Ex Output:
three

Ex Input:
Bovine insulin differs from human in only _ amino acid residues, and porcine insulin in one.

Ex Output:
three