// 私は猫です

#include<bits/stdc++.h>
#define ull unsigned long long
#define ll long long
#define pb push_back
#define mkp make_pair
#define fi first
#define se second
#define inf 1000000000
#define infll 1000000000000000000ll
#define pii pair<int,int>
#define rep(i,a,b,c) for(int i=(a);i<=(b);i+=(c))
#define per(i,a,b,c) for(int i=(a);i>=(b);i-=(c))
#define F(i,a,b) for(int i=(a);i<=(b);i++)
#define dF(i,a,b) for(int i=(a);i>=(b);i--)
#define cmh(sjy) while(sjy--)
#define lowbit(x) (x&(-x))
#define HH printf("\n")
#define eb emplace_back
#define poly vector<int>
using namespace std;
ll read(){
	ll x=0,f=1;char c=getchar();
	while(c<'0'||c>'9'){if(c=='-') f=-1;c=getchar();}
	while(c>='0'&&c<='9') x=(x<<3)+(x<<1)+(c^48),c=getchar();
	return x*f;
}
const int mod=998244353,maxn=500005;
inline int qpow(int x,ll y){
	int rt=1;
	for(;y;y>>=1,x=1ll*x*x%mod) if(y&1) rt=1ll*rt*x%mod;
	return rt;
}
inline void inc(int &x,int y){ x=(x+y>=mod)?(x+y-mod):(x+y); }
inline void dec(int &x,int y){ x=(x>=y)?(x-y):(x+mod-y); }
inline void mul(int &x,int y){ x=1ll*x*y%mod; }
inline int add(int x,int y){ return (x+y>=mod)?(x+y-mod):(x+y); }
inline int sub(int x,int y){ return (x>=y)?(x-y):(x+mod-y); }
inline int prod(int x,int y){ return 1ll*x*y%mod; }
inline void chkmax(int &x,int y){ x=max(x,y); }
inline void chkmin(int &x,int y){ x=min(x,y); }
vector<int>Wn,rev;
void init_NTT(int N=500005){
	Wn.resize(N);
	F(i,1,__lg(N)){
		int wn=qpow(3,(mod-1)/(1<<i)),now=1;
		for(int j=0;j<(1<<(i-1));j++) Wn[(1<<(i-1))+j]=now,mul(now,wn);
	}
}
vector<int>add(vector<int>a,vector<int>b){
	if(a.size()<b.size())swap(a,b);
	F(i,0,(int)b.size()-1)inc(a[i],b[i]);
	return a;
}
void NTT(vector<int>&a,int N,int op=1){
	int n=a.size(),p=1,k=0;
	for(;p<n;p<<=1,k++);
	rev.resize(n+1);
	F(i,1,n-1) rev[i]=(rev[i>>1]>>1)|((i&1)<<(k-1));
	F(i,0,n-1) if(i<rev[i]) swap(a[i],a[rev[i]]);
	F(i,1,k) for(int j=0;j<(1<<k);j+=(1<<i)){
		int tmp=(1<<(i-1));
		F(l,j,j+tmp-1){
			int x=a[l],y=prod(a[l+tmp],Wn[tmp+l-j]);
			a[l]=add(x,y),a[l+tmp]=sub(x,y);
		}
	}
	if(~op) return;
	reverse(a.begin()+1,a.end());
	a.resize(N);
	for(k=1;k<=N;k<<=1);
	int inv=qpow(k,mod-2);
	F(i,0,N-1) mul(a[i],inv);
}
vector<int>conv(vector<int>a,vector<int>b){
	int n=(int)a.size(),m=(int)b.size(),k=1;
	for(;k<n+m;k<<=1);
	a.resize(k),b.resize(k);
	NTT(a,n,1),NTT(b,m,1);
	F(i,0,k-1) mul(a[i],b[i]);
	NTT(a,n+m-1,-1);
	return a;
}
vector<int>getinv(int n,vector<int>a){
	if(n==1) {
		vector<int>vec;
		vec.push_back(qpow(a[0],mod-2));
		return vec;
	}
	vector<int>b=getinv((n+1)>>1,a),c;
	F(i,0,n-1) c.push_back(a[i]);
	int p=1;
	for(;p<(n<<1);p<<=1);
	c.resize(p),b.resize(p);
	NTT(c,n,1),NTT(b,n,1);
	F(i,0,p-1) c[i]=1ll*b[i]*sub(2,1ll*b[i]*c[i]%mod)%mod;
	NTT(c,p-1,-1);
	c.resize(n);
	return c;
}
int n,m,coef[maxn],pre[maxn];
namespace combi{
	int fac[maxn],ifac[maxn],inv[maxn],pw[maxn];
	void Init(int N){
		fac[0]=ifac[0]=inv[0]=pw[0]=1;
		F(i,1,N) pw[i]=1ll*pw[i-1]*m%mod;
		F(i,1,N) fac[i]=1ll*fac[i-1]*i%mod;
		ifac[N]=qpow(fac[N],mod-2);
		dF(i,N-1,1) ifac[i]=1ll*ifac[i+1]*(i+1)%mod;
		F(i,1,N) inv[i]=1ll*ifac[i]*fac[i-1]%mod;
	}
	inline int C(int n,int m){
		if(m>n||n<0||m<0) return 0;
		return 1ll*fac[n]*ifac[m]%mod*ifac[n-m]%mod;
	}
}
using namespace combi;
void solve(){
	n=read(),m=read(),Init(maxn-3);
	F(i,0,n) pre[i]=C(n,i);
	F(i,1,n) inc(pre[i],pre[i-1]);
	vector<int>f(n+1),g(n+1);
	F(i,0,n){
		if(i<=(n>>1)) f[i]=add(pre[i-1],1ll*C(n,i)*(n-(i<<1))%mod);
		else f[i]=pre[n-i-1];
		mul(f[i],fac[n-i]);
	}
	F(i,0,n) g[i]=(i&1)?ifac[i]:mod-ifac[i];
	g=conv(f,g);
	F(i,0,n) coef[i]=1ll*g[i]*pw[n-i]%mod*ifac[n-i]%mod;
	f.resize(n+2),g.resize(n+2);
	F(i,0,n+1) f[i]=ifac[i+1];
	f=getinv(n+2,f);
	int tot=1;
	F(i,0,n+1) g[i]=1ll*tot*ifac[i]%mod,mul(tot,m+1);
	g=conv(f,g);
	int ans=1ll*n*(m-1)%mod*pw[n]%mod;
	mul(ans,((mod+1)>>1));
	F(i,0,n) inc(ans,1ll*coef[i]*sub(g[i+1],f[i+1])%mod*fac[i]%mod);
	dec(ans,coef[0]);
	printf("%d\n",ans);
}
signed main(){
	init_NTT();
	int sjy=1;
	cmh(sjy) solve();
}