write a go solution for Description:
Your task is to calculate the number of arrays such that:

- each array contains n elements;
- each element is an integer from 1 to m;
- for each array, there is exactly one pair of equal elements;
- for each array a, there exists an index i such that the array is strictly ascending before the i-th element and strictly descending after it (formally, it means that a_j<a_j+1, if j<i, and a_j>a_j+1, if j>=i).

Input Format:
The first line contains two integers n and m (2<=n<=m<=2*10^5).

Output Format:
Print one integer — the number of arrays that meet all of the aforementioned conditions, taken modulo 998244353.

Note:
The arrays in the first example are:

- [1,2,1];
- [1,3,1];
- [1,4,1];
- [2,3,2];
- [2,4,2];
- [3,4,3].. Output only the code with no comments, explanation, or additional text.