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.

Sentence 1: US Cannot 'Conclusively Determine' Chemical Weapons Use in Syria Sentence 2: U.S. Sees No Conclusive Evidence of Chemical Arms Use by Syria
5

Sentence 1: The broader Standard & Poor's 500 Index <.SPX> was up 9.69 points, or 0.98 percent, at 994.53. Sentence 2: The tech-laced Nasdaq Composite Index <.IXIC> gained 18.35 points, or 1.13 percent, to 1,646.02.
1

Sentence 1: A man is carrying another man. Sentence 2: A man sprays another man with water from a hose.

1