#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';
}

#include<bits/stdc++.h>
using namespace std;
const int N=5005,mod=998244353;
int n,m,ans,f[N][2],g[N][2];
inline int add(int a,int b){
	a+=b;
	return a<mod?a:a-mod;
}
inline int dec(int a,int b){
	a-=b;
	return a<0?a+mod:a;
}
inline int mul(int a,int b){
	return 1LL*a*b%mod;
}
int main(){
	scanf("%d%d",&n,&m);
	for(int i=1;i<=m;i++){
		memset(f,0,sizeof(f));
		memset(g,0,sizeof(f));
		f[0][0]=1;
		g[0][0]=0;
		for(int j=1;j<=n;j++){
			f[j][0]=add(mul(f[j-1][0],m-1),mul(f[j-1][1],i-1));
			g[j][0]=add(mul(g[j-1][0],m-1),mul(g[j-1][1],i-1));
			f[j][1]=add(f[j-1][0],mul(f[j-1][1],m-i+1));
			if(j==n){
				j++;
				j--;
			}
			g[j][1]=add(g[j-1][0],f[j-1][0]);
			g[j][1]=add(g[j][1],mul(g[j-1][1],m-i+1));
		}
		ans=add(ans,add(g[n][0],g[n][1]));
	}
	printf("%d\n",ans);
	return 0;
}