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

Input: Consider Input: Diatoms are in _ shells and make the water brown.

Output: two


Input: Consider Input: Plants have many white flowers with _ petals, giving the plant a white, flat-topped appearance.

Output: four


Input: Consider Input: Protein synthesis involves _ parts, transcription and translation.


Output: two