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

Ex Input:
Pelycosaurs are a paraphyletic group of _ primitive families of synapsids.

Ex Output:
six

Ex Input:
Woodchucks can dig up to _ entrances to one den.

Ex Output:
three

Ex Input:
Carbon dioxide extinguishes fire by physically attacking all _ points of the fire triangle.

Ex Output:
three