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: X'mas cruise passengers hit by Norovirus Sentence 2: Missing cruise passenger is a NSW ambo
Example Output: 0

Example Input: Sentence 1: a train rides on his tracks. Sentence 2: The train comes down the track, between two rows of trees.
Example Output: 3

Example Input: Sentence 1: A computer on a desk. Sentence 2: A computer operating on a desk.
Example Output:
4