E1. Abnormal Permutation Pairs (easy version)time limit per test1 secondmemory limit per test512 megabytesinputstandard inputoutputstandard outputThis is the easy version of the problem. The only difference between the easy version and the hard version is the constraints on n. You can only make hacks if both versions are solved.A permutation of 1, 2, \ldots, n is a sequence of n integers, where each integer from 1 to n appears exactly once. For example, [2,3,1,4] is a permutation of 1, 2, 3, 4, but [1,4,2,2] isn't because 2 appears twice in it.Recall that the number of inversions in a permutation a_1, a_2, \ldots, a_n is the number of pairs of indices (i, j) such that i < j and a_i > a_j.Let p and q be two permutations of 1, 2, \ldots, n. Find the number of permutation pairs (p,q) that satisfy the following conditions:  p is lexicographically smaller than q.  the number of inversions in p is greater than the number of inversions in q. Print the number of such pairs modulo mod. Note that mod may not be a prime.InputThe only line contains two integers n and mod (1\le n\le 50, 1\le mod\le 10^9).OutputPrint one integer, which is the answer modulo mod.ExampleInput
4 403458273
Output
17NoteThe following are all valid pairs (p,q) when n=4.  p=[1,3,4,2], q=[2,1,3,4],  p=[1,4,2,3], q=[2,1,3,4],  p=[1,4,3,2], q=[2,1,3,4],  p=[1,4,3,2], q=[2,1,4,3],  p=[1,4,3,2], q=[2,3,1,4],  p=[1,4,3,2], q=[3,1,2,4],  p=[2,3,4,1], q=[3,1,2,4],  p=[2,4,1,3], q=[3,1,2,4],  p=[2,4,3,1], q=[3,1,2,4],  p=[2,4,3,1], q=[3,1,4,2],  p=[2,4,3,1], q=[3,2,1,4],  p=[2,4,3,1], q=[4,1,2,3],  p=[3,2,4,1], q=[4,1,2,3],  p=[3,4,1,2], q=[4,1,2,3],  p=[3,4,2,1], q=[4,1,2,3],  p=[3,4,2,1], q=[4,1,3,2],  p=[3,4,2,1], q=[4,2,1,3]. 
4 403458273

17
['combinatorics', 'dp', 'fft', 'math', '*2400']