题目描述
You are given a set of points $x_1$, $x_2$, ..., $x_n$ on the number line.
Two points $i$ and $j$ can be matched with each other if the following conditions hold:
- neither $i$ nor $j$ is matched with any other point;
- $|x_i - x_j| \ge z$.
What is the maximum number of pairs of points you can match with each other?
Input
The first line contains two integers $n$ and $z$ ($2 \le n \le 2 \cdot 10^5$, $1 \le z \le 10^9$) — the number of points and the constraint on the distance between matched points, respectively.
The second line contains $n$ integers $x_1$, $x_2$, ..., $x_n$ ($1 \le x_i \le 10^9$).
Output
Print one integer — the maximum number of pairs of points you can match with each other.
输入格式
见题面 Input 部分
输出格式
见题面 Output 部分
样例输入
样例输出
提示
In the first example, you may match point $1$ with point $2$ ($|3 - 1| \ge 2$), and point $3$ with point $4$ ($|7 - 3| \ge 2$).
In the second example, you may match point $1$ with point $3$ ($|5 - 10| \ge 5$).