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.

Ex Input:
Sentence 1: An airplane is flying in the air. Sentence 2: A South African Airways plane is flying in a blue sky.

Ex Output:
3


Ex Input:
Sentence 1: David @OmSigDAVID, I think Santorum's more likely than Gingrich. Sentence 2: @sozobe, I think Santorum's more likely than Gingrich.

Ex Output:
5


Ex Input:
Sentence 1: Four other men who were also charged in June have already pleaded guilty. Sentence 2: Four of the defendants have pleaded guilty to weapons charges and other counts.

Ex Output:

3