Counting Pairs

Count the distinct ordered value pairs (a,b) in the array such that a+k=b. The same index may serve as both a and b, so when k=0 every distinct value can pair with itself.

输入格式

The first line contains n k (2≤n≤200000, 0≤k≤10⁹), and the second line contains n numbers (0..10⁹).

输出格式

Output a single integer answer.

样例 1

输入：

4 1
1 1 1 2

输出：

1

样例 2

输入：

2 0
1 2

输出：

2

样例 3

输入：

4 2
1 3 5 7

输出：

3

样例说明

Example 1: only (1,2); the repeated 1 does not increase the answer, so the result is 1. Example 2: (1,1) and (2,2) are both valid, so the result is 2. Example 3: (1,3), (3,5), (5,7), so the result is 3.