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

Ex Input:
Pelagic division is divided into neritic and _ levels of pelagic provinces.

Ex Output:
three

Ex Input:
Thermal equilibrium occurs when _ bodies have the same temperature.

Ex Output:
two

Ex Input:
Birds have a reversed rear toe that opposes the front _ toes and allows birds to perch.

Ex Output:
three