You will be given a definition of a task first, then some input of the task.
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: russia had threatened several times to withdraw from the cfe when it was at odds with the united states over u.s. plans to install a missile defense shield in eastern Sentence 2: russia has repeatedly threatened withdrawal from the cfe in opposition to plans for the extension of the us missile defense shield to eastern europe.
Output:
5