Your math professor is writing a list of unique numbers and is asking you to give him the number of pairs whose sum is equal to X. The professor is very busy now and wants you to do the calculations quickly and to give him the final result.

Question: Given a list of n unique numbers, output the number of pairs whose sum is equal to X.

Input specification:
In the first line you will be given two integers n and X (5 <= n <= 200.000, -100.000 <= X <= 100.000), where n determines the number of integers that the list will contain and X determines the sum which the numbers of each pair should give as their sum when added to each other. In the following line, you will be given n integers (-100.000 <= nr <= 100.000).

Output specification:
Write a single number, the number of pairs whose sum is equal to X.