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: Black train on train tracks. Sentence 2: A train on the train tracks.
4

Sentence 1: Thai opposition protesters begin Bangkok shutdown Sentence 2: Thai protesters launch Bangkok 'shutdown'
5

Sentence 1: A dog leaps off a dock and into the water. Sentence 2: The black dog leaps off the dock and into the water.

4