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: It's so stupid that it just has to be true. Sentence 2: It's amusing to think it even might be true.
3

Sentence 1: A man walking down the stairs. Sentence 2: A man walks down a staircase.
5

Sentence 1: For the full 12-month period ending June 30, 2003, advanced services lines for ADSL increased by 37 percent and cable modem connections increased by 75 percent. Sentence 2: For the 12-month period ending June 30, high-speed lines installed in homes and businesses increased by 45 percent.

2