B'This is the first subtask of problem F. The only differences between this and the second subtask are the constraints on the value of m and the time limit. You need to solve both subtasks in order to hack this one. There are n+1 distinct colours in the universe, numbered 0 through n . There is a strip of paper m centimetres long initially painted with colour 0 . Alice took a brush and painted the strip using the following process. For each i from 1 to n , in this order, she picks two integers 0 <= q a_i < b_i <= q m , such that the segment [a_i, b_i] is currently painted with a single colour, and repaints it with colour i . Alice chose the segments in such a way that each centimetre is now painted in some colour other than 0 . Formally, the segment [i-1, i] is painted with colour c_i ( c_i neq 0 ). Every colour other than 0 is visible on the strip. Count the number of different pairs of sequences {a_i }_{i=1}^n , {b_i }_{i=1}^n that result in this configuration. Since this number may be large, output it modulo 998244353 . The first line contains a two integers n , m ( 1 <= q n <= q 500 , n = m ) -- the number of colours excluding the colour 0 and the length of the paper, respectively. The second line contains m space separated integers c_1, c_2, ldots, c_m ( 1 <= q c_i <= q n ) -- the colour visible on the segment [i-1, i] after the process ends. It is guaranteed that for all j between 1 and n there is an index k such that c_k = j . Note that since in this subtask n = m , this means that c is a permutation of integers 1 through n . Output a single integer -- the number of ways Alice can perform the painting, modulo 998244353 . In the first example, there are 5 ways, all depicted in the figure below. Here, 0 is white, 1$'...