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.

Q: Sentence 1: A man walking down the stairs. Sentence 2: A man walks down a staircase.

A: 5
****
Q: Sentence 1: Algerian priest to lecture about Christian heritage in N. Africa Sentence 2: Telstra applies to list China site in NY

A: 0
****
Q: Sentence 1: Hey, Blue-Eyes, How's things in London? Sentence 2: **smooches Ran** Hey, Blue-Eyes, How's things in London?

A:
4
****