Detailed Instructions: In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 
Q: You take some paper. The writing tools. You write a message describing what's on your mind. You put the letter into an envelope. You take the letter to the post office. Send it to its recipient. 
A:
paper ,writing tool ,message ,letter 