#include <bits/stdc++.h>
using namespace std;
constexpr long long mod = 998244353;

long long modpow(int n, int r) {
    long long ret = 1; long long tmp = (long long) n;
    while (r != 0) {
        if (r % 2) ret *= tmp;
        tmp *= tmp; tmp %= mod; ret %= mod;
        r /= 2;
    }
    return ret;
}


int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int N, M; cin >> N >> M;
    long long Ans = 0;
    vector<long long> M_pow(N+1, 1);
    for (int i = 0; i < N; i++) {
        M_pow[i+1] = M_pow[i] * M % mod;
    }
    for (int min_val = 1; min_val <= M; min_val++) {
        for (int interval = 2; interval <= N; interval++) {
            long long fac = N - interval + 1;
            long long tmp = modpow(M - min_val, interval - 2) * M_pow[N - interval] % mod;
            Ans += fac * tmp % mod;
            Ans %= mod;
            // cout << min_val << " " << interval << " " <<  fac << tmp % mod << "\n";
        }
    }
    Ans = mod + M_pow[N] * N % mod - Ans;
    cout << Ans % mod << "\n";
    return 0;
}
#include <bits/stdc++.h>
using namespace std;

template <int MOD_> struct modnum {
	static constexpr int MOD = MOD_;
	static_assert(MOD_ > 0, "MOD must be positive");

private:
	using ll = long long;

	int v;

	static int minv(int a, int m) {
		a %= m;
		assert(a);
		return a == 1 ? 1 : int(m - ll(minv(m, a)) * ll(m) / a);
	}

public:

	modnum() : v(0) {}
	modnum(ll v_) : v(int(v_ % MOD)) { if (v < 0) v += MOD; }
	explicit operator int() const { return v; }
	friend std::ostream& operator << (std::ostream& out, const modnum& n) { return out << int(n); }
	friend std::istream& operator >> (std::istream& in, modnum& n) { ll v_; in >> v_; n = modnum(v_); return in; }

	friend bool operator == (const modnum& a, const modnum& b) { return a.v == b.v; }
	friend bool operator != (const modnum& a, const modnum& b) { return a.v != b.v; }

	modnum inv() const {
		modnum res;
		res.v = minv(v, MOD);
		return res;
	}
	friend modnum inv(const modnum& m) { return m.inv(); }
	modnum neg() const {
		modnum res;
		res.v = v ? MOD-v : 0;
		return res;
	}
	friend modnum neg(const modnum& m) { return m.neg(); }

	modnum operator- () const {
		return neg();
	}
	modnum operator+ () const {
		return modnum(*this);
	}

	modnum& operator ++ () {
		v ++;
		if (v == MOD) v = 0;
		return *this;
	}
	modnum& operator -- () {
		if (v == 0) v = MOD;
		v --;
		return *this;
	}
	modnum& operator += (const modnum& o) {
		v += o.v;
		if (v >= MOD) v -= MOD;
		return *this;
	}
	modnum& operator -= (const modnum& o) {
		v -= o.v;
		if (v < 0) v += MOD;
		return *this;
	}
	modnum& operator *= (const modnum& o) {
		v = int(ll(v) * ll(o.v) % MOD);
		return *this;
	}
	modnum& operator /= (const modnum& o) {
		return *this *= o.inv();
	}

	friend modnum operator ++ (modnum& a, int) { modnum r = a; ++a; return r; }
	friend modnum operator -- (modnum& a, int) { modnum r = a; --a; return r; }
	friend modnum operator + (const modnum& a, const modnum& b) { return modnum(a) += b; }
	friend modnum operator - (const modnum& a, const modnum& b) { return modnum(a) -= b; }
	friend modnum operator * (const modnum& a, const modnum& b) { return modnum(a) *= b; }
	friend modnum operator / (const modnum& a, const modnum& b) { return modnum(a) /= b; }
};

template <typename T> T pow(T a, long long b) {
	assert(b >= 0);
	T r = 1; while (b) { if (b & 1) r *= a; b >>= 1; a *= a; } return r;
}

using num = modnum<998244353>;

vector<num> fact, ifact;

void init(){
	int N = 1100000;
	fact = {1};
	for(int i = 1; i < N; i++) fact.push_back(i * fact[i-1]);
	ifact.resize(N);
	ifact.back() = 1 / fact.back();
	for(int i = N - 1; i > 0; i--) ifact[i-1] = i * ifact[i];
}

num ncr(int n, int k){
	if(k < 0 || k > n) return 0;
	return fact[n] * ifact[k] * ifact[n-k];
}

int main(){
	ios_base::sync_with_stdio(false), cin.tie(nullptr);
	init();
	int n, m;
	cin >> n >> m;
	num ans = pow(num(m), n) * n;
	vector<num> r(m, 1);
	for(int len = 1; len < n; len++){
		num mult = pow(num(m), n-1-len) * (n-len);
		num v = 0;
		for(int a = 0; a < m; a++){
			v += r[a];
			r[a] *= a;
		}
		ans -= mult * v;
	}
	cout << ans << '\n';
}
