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 man drove his car. Sentence 2: A man is driving a car.
Example Output: 4

Example Input: Sentence 1: The cat played with a watermelon. Sentence 2: A cat is playing with a watermelon.
Example Output: 5

Example Input: Sentence 1: Syrian Arab Republic (the): Syrian Arab Republic: Syrian Refugees (as of 28 June 2012) Sentence 2: Syrian Arab Republic (the): More than 70 killed in Syria ahead of Annan return
Example Output:
1