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.

Example Input: Sentence 1: A woman is riding an elephant. Sentence 2: A man is lifting himself.
Example Output: 0

Example Input: Sentence 1: Usain Bolt wins 200m – Steven Howard reaction Sentence 2: Facebook mobile gains drive revenue growth: reaction
Example Output: 0

Example Input: Sentence 1: A woman is shooting a gun. Sentence 2: A woman shoots a shotgun.
Example Output:
4