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

Ex Input:
Trees can also be air layered but air layering usually takes four to _ months to be successful.

Ex Output:
six

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

Ex Output:
one

Ex Input:
Martens produce _ litter per year, with an average of slightly less than three young per female.

Ex Output:
one