CF742B Arpa’s obvious problem and Mehrdad’s terrible solution

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

First line contains two integers $ n $ and $ x $ ( $ 1

Print a single integer: the answer to the problem.

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).