Arpa’s obvious problem and Mehrdad’s terrible solution

题意翻译

给出一串数组a1..an，和一个数字x，询问有多少对ai,aj满足ai^aj=x

题目描述

There are some beautiful girls in Arpa’s land as mentioned before. Once Arpa came up with an obvious problem: Given an array and a number $ x $ , count the number of pairs of indices $ i,j $ ( $ 1<=i&lt;j<=n $ ) such that , where  is bitwise xor operation (see notes for explanation). Immediately, Mehrdad discovered a terrible solution that nobody trusted. Now Arpa needs your help to implement the solution to that problem.

输入输出格式

输入格式

First line contains two integers $ n $ and $ x $ ( $ 1<=n<=10^{5},0<=x<=10^{5} $ ) — the number of elements in the array and the integer $ x $ . Second line contains $ n $ integers $ a_{1},a_{2},...,a_{n} $ ( $ 1<=a_{i}<=10^{5} $ ) — the elements of the array.

输出格式

Print a single integer: the answer to the problem.

输入输出样例

输入样例 #1

2 3
1 2

输出样例 #1

1

输入样例 #2

6 1
5 1 2 3 4 1

输出样例 #2

2

说明

In the first sample there is only one pair of $ i=1 $ and $ j=2 $ .  so the answer is $ 1 $ . In the second sample the only two pairs are $ i=3 $ , $ j=4 $ (since ) and $ i=1 $ , $ j=5 $ (since ). A bitwise xor takes two bit integers of equal length and performs the logical xor operation on each pair of corresponding bits. The result in each position is $ 1 $ if only the first bit is $ 1 $ or only the second bit is $ 1 $ , but will be $ 0 $ if both are $ 0 $ or both are $ 1 $ . You can read more about bitwise xor operation here: [https://en.wikipedia.org/wiki/Bitwise\_operation#XOR](https://en.wikipedia.org/wiki/Bitwise_operation#XOR).