E1. Median on Segments (Permutations Edition)time limit per test3 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputYou are given a permutation p_1, p_2, \dots, p_n. A permutation of length n is a sequence such that each integer between 1 and n occurs exactly once in the sequence.Find the number of pairs of indices (l, r) (1 \le l \le r \le n) such that the value of the median of p_l, p_{l+1}, \dots, p_r is exactly the given number m.The median of a sequence is the value of the element which is in the middle of the sequence after sorting it in non-decreasing order. If the length of the sequence is even, the left of two middle elements is used.For example, if a=[4, 2, 7, 5] then its median is 4 since after sorting the sequence, it will look like [2, 4, 5, 7] and the left of two middle elements is equal to 4. The median of [7, 1, 2, 9, 6] equals 6 since after sorting, the value 6 will be in the middle of the sequence.Write a program to find the number of pairs of indices (l, r) (1 \le l \le r \le n) such that the value of the median of p_l, p_{l+1}, \dots, p_r is exactly the given number m.InputThe first line contains integers n and m (1 \le n \le 2\cdot10^5, 1 \le m \le n) — the length of the given sequence and the required value of the median.The second line contains a permutation p_1, p_2, \dots, p_n (1 \le p_i \le n). Each integer between 1 and n occurs in p exactly once.OutputPrint the required number.ExamplesInput5 42 4 5 3 1Output4Input5 51 2 3 4 5Output1Input15 81 15 2 14 3 13 4 8 12 5 11 6 10 7 9Output48NoteIn the first example, the suitable pairs of indices are: (1, 3), (2, 2), (2, 3) and (2, 4).
Input5 42 4 5 3 1
Output4
['sortings', '*1800']