Given the task definition and input, reply with output. 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: Heather, 35, who lost a leg in a road accident, is thought to have steel plates fitted in her hips, which would make natural childbirth impossible. Sentence 2: Former model Lady McCartney lost a leg in a road accident in 1993 and is understood to have steel plates fitted in her hips which would make natural childbirth difficult.
2