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: five people standing on a sidewalk Sentence 2: Five people on a sidewalk.
5

Sentence 1: A man is straining pasta. Sentence 2: A man plays a wooden flute.
0

Sentence 1: That exploit works on unpatched Windows 2000 machines with Service Pack 3 and 4. Sentence 2: Both Counterpane and iDefense contend that the exploit works effectively against Windows 2000 systems running Service Pack 3 and 4.

3