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

Ex Input:
Boolean operations is a method of combining _ meshes together.

Ex Output:
two


Ex Input:
Echocardiography demonstrates in clear, graphic fashion the _ cardiac chambers and four valves.

Ex Output:
four


Ex Input:
Calves begin to take a few fish at about three to _ months.

Ex Output:

four