#include <bits/stdc++.h>
using namespace std;

typedef long long ll;

const int N = 1e6 + 5;

const ll mod = 998244353;

ll fac[N], ifac[N];

inline void get_fac(ll n) {
	fac[0] = 1;
	for (int i = 1; i <= n; ++i) {
		fac[i] = fac[i - 1] * i % mod;
	}
	ifac[0] = ifac[1] = 1;
	for (int i = 2; i <= n; ++i) {
		ifac[i] = (mod - mod / i) * ifac[mod % i] % mod;
	}
	for (int i = 1; i <= n; ++i) {
		ifac[i] = ifac[i] * ifac[i - 1] % mod;
	}
}

inline ll A(ll n, ll m) {
	if (n < m) {
		return 0;
	}
	return fac[n] * ifac[n - m] % mod;
}

inline ll C(ll n, ll m) {
	if (n < m) {
		return 0;
	}
	return fac[n] * ifac[m] % mod * ifac[n - m] % mod;
}

inline ll qpow(ll a, ll b) {
	ll res = 1;
	while (b) {
		if (b & 1) {
			res = res * a % mod;
		}
		a = a * a % mod;
		b >>= 1;
	}
	return res;
}

inline ll inv(ll a) {
	return qpow(a, mod - 2);
}

ll n, m, ans;

inline void addmod(ll &x) {
	(x >= mod) && (x -= mod);
}

int main() {
	#ifdef LOCAL
		assert(freopen("test.in", "r", stdin));
		assert(freopen("test.out", "w", stdout));
	#endif
	ios::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
	get_fac(1e6);
	cin >> n >> m;
	for (int i = 1; i <= m; ++i) {
		addmod(ans += qpow(m, n));
		addmod(ans += mod - qpow(i - 1, n));
	}
	addmod(ans <<= 1);
	addmod(ans = ans + mod - qpow(m, n));
	cout << ans << "\n";
	return 0;
}