A13308. Pair of Topics

The next lecture in a high school requires two topics to be discussed. The $i$ -th topic is interesting by $a_i$ units for the teacher and by $b_i$ units for the students.

The pair of topics $i$ and $j$ ( $i < j$ ) is called good if $a_i + a_j > b_i + b_j$ (i.e. it is more interesting for the teacher).

Your task is to find the number of good pairs of topics.

The first line of the input contains one integer $n$ ( $2 \le n \le 2 \cdot 10^5$ ) — the number of topics.

The second line of the input contains $n$ integers $a_1, a_2, \dots, a_n$ ( $1 \le a_i \le 10^9$ ), where $a_i$ is the interestingness of the $i$ -th topic for the teacher.

The third line of the input contains $n$ integers $b_1, b_2, \dots, b_n$ ( $1 \le b_i \le 10^9$ ), where $b_i$ is the interestingness of the $i$ -th topic for the students.

Print one integer — the number of good pairs of topic.