Given the task definition and input, reply with output. In this task, you are given two sentences in the English language (Sentence 1 and Sentence 2). Your task is to identify the connecting word between the two sentences.

Sentence 1:Therefore , the number of incident pairs is the sum of the degrees . Sentence 2:However , each edge in the graph belongs to exactly two incident pairs , one for each of its endpoints ; therefore , the number of incident pairs is 2
however