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: amnesty international is a rights group based in london. Sentence 2: the international institute for strategic studies is located in london.
1

Sentence 1: A little boy clowns with a colander on his head. Sentence 2: A boy with a metal colander on his head.
4

Sentence 1: A man is playing the piano. Sentence 2: A woman is playing the violin.

1