#ifndef CLASS_MODINT
#define CLASS_MODINT

#include <cstdint>

template <std::uint32_t mod>
class modint {
private:
	std::uint32_t n;
public:
	modint() : n(0) {};
	modint(std::int64_t n_) : n((n_ >= 0 ? n_ : mod - (-n_) % mod) % mod) {};
	static constexpr std::uint32_t get_mod() { return mod; }
	std::uint32_t get() const { return n; }
	bool operator==(const modint& m) const { return n == m.n; }
	bool operator!=(const modint& m) const { return n != m.n; }
	modint& operator+=(const modint& m) { n += m.n; n = (n < mod ? n : n - mod); return *this; }
	modint& operator-=(const modint& m) { n += mod - m.n; n = (n < mod ? n : n - mod); return *this; }
	modint& operator*=(const modint& m) { n = std::uint64_t(n) * m.n % mod; return *this; }
	modint operator+(const modint& m) const { return modint(*this) += m; }
	modint operator-(const modint& m) const { return modint(*this) -= m; }
	modint operator*(const modint& m) const { return modint(*this) *= m; }
	modint inv() const { return (*this).pow(mod - 2); }
	modint pow(std::uint64_t b) const {
		modint ans = 1, m = modint(*this);
		while (b) {
			if (b & 1) ans *= m;
			m *= m;
			b >>= 1;
		}
		return ans;
	}
};

#endif // CLASS_MODINT

#include <vector>
#include <iostream>
using namespace std;
using mint = modint<998244353>;

int main() {
	// step #1. read input
	int N, M;
	cin >> N >> M;
	
	// step #2. dynamic programming
	vector<vector<mint> > dp(N + 1, vector<mint>(M + 1));
	vector<vector<mint> > dpsum(N + 2, vector<mint>(M + 1));
	vector<mint> dpsum2(N + 2);
	dp[0][0] = 1;
	dpsum[1][0] = 1;
	dpsum2[1] = 1;
	for (int i = 1; i <= N; i++) {
		for (int j = 1; j <= M; j++) {
			int l = max(i - j + 1, 0);
			dp[i][j] += dpsum2[i] - dpsum2[l];
			dp[i][j] -= dpsum[i][j] - dpsum[l][j];
			dpsum[i + 1][j] = dpsum[i][j] + dp[i][j];
		}
		dpsum[i + 1][0] = 1;
		for (int j = 0; j <= M; j++) {
			dpsum2[i + 1] += dpsum[i + 1][j];
		}
	}
	
	// step #3. final answer
	mint subanswer = 0;
	for (int i = 1; i <= M; i++) {
		subanswer += dp[N][i];
	}
	mint answer = mint(M).pow(N) - subanswer;
	cout << answer.get() << endl;
	
	return 0;
}