Evaluate the similarity between them and classify them into classes from 0-5 as follows:
0 : The two sentences are completely dissimilar.
1 : The two sentences are not equivalent, but are on the same topic.
2 : The two sentences are not equivalent, but share some details.
3 : The two sentences are roughly equivalent, but some important information differs/missing.
4 : The two sentences are mostly equivalent, but some unimportant details differ.
5 : The two sentences are completely equivalent, as they mean the same thing.

Sentence 1: A person wearing a helmet rides a bike near a white structure. Sentence 2: A person wearing a bike helmet rides a bike on a path through trees.
3

Sentence 1: Cisco executives said they were encouraged by $1.3 billion in cash flow and the increase in net income, but hoped for a rebound. Sentence 2: Cisco executives were encouraged by $1.3 billion in cash flow and the increase in net income, but said they remained ``cautiously optimistic'' about a rebound.
5

Sentence 1: What is your definition of "life"? Sentence 2: What's your definition of nature?

1