#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define ull unsigned long long
#define ulll __uint128_t
#define eb emplace_back
#define po pop_back
#define mid ((l+r)/2)
#define mod FM.reduce
const int N=(1<<23)+5;
int fc[N],invfc[N];
int MOD,g1,lim,lim1,invl,r[N],g[2][N];
struct FastMod
{
	ull p,w;FastMod(ull p=2):p(p),w((ull)(((ulll)(1)<<64)/p)) {}
    ull reduce(ull x) {ull d=(ull)(((ulll)(w)*x)>>64),r=x-p*d;return r>=p?r-p:r;}
}FM;
void W(int &x,int y) {x+=y;if(x>=MOD) x-=MOD;}
void W(int &x,ll y) {x=mod(x+y);}
void W(int &x,ull y) {x=mod(x+y);}
int W1(int x,int y) {x+=y;return x<MOD?x:x-MOD;}
int qpow(int x,int y)
{int res=1;for(;y;y>>=1,x=mod(1ll*x*x)) if(y&1) res=mod(1ll*res*x);return res;}
void initg()
{
	int t=MOD-1;vector<int> p;
	for(int i=2;i*i<=t;++i) if(!(t%i)) {p.eb(i);while(!(t%i)) t/=i;}
	if(t>1) p.eb(t);
	for(int i=2;;++i)
	{
		bool fl=1;for(auto j:p) if(qpow(i,(MOD-1)/j)==1) {fl=0;break;}
		if(fl) {g1=i;break;}
	}
}
void init(int n)
{
	int l=0;lim=1;while(lim<n) ++l,lim*=2;invl=qpow(lim,MOD-2);
	for(int i=0;i<lim;++i) r[i]=(r[i>>1]>>1)|((i&1)<<l-1);
	if(lim>lim1)
	{
		for(int i=1,t1,t2,t3,t4;i<lim;i*=2)
		{
			t1=qpow(g1,(MOD-1)/(i*2));t2=qpow(t1,MOD-2);t3=t4=1;
			for(int j=0;j<i;++j,t3=mod(1ll*t3*t1),t4=mod(1ll*t4*t2))
				g[0][i+j]=t3,g[1][i+j]=t4;
		}lim1=lim;
	}
}
void init1(int n)
{
    fc[0]=1;for(int i=1;i<=n;++i) fc[i]=mod(1ll*fc[i-1]*i);
    invfc[n]=qpow(fc[n],MOD-2);
    for(int i=n;i;--i) invfc[i-1]=mod(1ll*invfc[i]*i);
}
int bn(int x,int y) {return x<y || y<0?0:mod(mod(1ll*fc[x]*invfc[y])*invfc[x-y]);}
int calc(int i,int j) {return mod(mod(1ll*bn(i+j-2,i-1)*bn(i+j-2,i-1))-mod(1ll*bn(i+j-2,i)*bn(i+j-2,j))+MOD);}
struct Poly
{
	vector<int> a;Poly(vector<int> _a={}) {a=_a;}
	Poly mv(int x)
	{
		Poly res;res.a.resize(a.size()+x);
		copy(a.begin(),a.end(),res.a.begin()+x);return res;
	}
	void NTT(bool fl)
	{
		a.resize(lim);for(int i=0;i<lim;++i) if(i<r[i]) swap(a[i],a[r[i]]);
		for(int i=1,t1,t2;i<lim;i*=2) for(int j=0;j<lim;j+=i*2) for(int k=0;k<i;++k)
		{
			t1=a[j+k];t2=mod(1ll*g[fl][i+k]*a[i+j+k]);
			a[j+k]=W1(t1,t2);a[i+j+k]=W1(t1,MOD-t2);
		}if(fl) for(int i=0;i<lim;++i) a[i]=mod(1ll*a[i]*invl); 
	}
	Poly operator + (const Poly &t) const
	{
		Poly res(a);if(a.size()<t.a.size()) res.a.resize(t.a.size());
		for(int i=0;i<t.a.size();++i) W(res.a[i],t.a[i]);return res;
	}
	Poly operator - (const Poly &t) const
	{
		Poly res(a);if(a.size()<t.a.size()) res.a.resize(t.a.size());
		for(int i=0;i<t.a.size();++i) W(res.a[i],MOD-t.a[i]);return res;
	}
	Poly operator * (Poly t) const
	{
		int n=a.size()+t.a.size()-1;Poly res(a);init(n);t.NTT(0);res.NTT(0);
		for(int i=0;i<lim;++i) res.a[i]=mod(1ll*res.a[i]*t.a[i]);res.NTT(1);
		res.a.resize(n);return res;
	}
	Poly operator * (int t) const
	{Poly res(a);for(auto &i:res.a) i=mod(1ll*i*t);return res;}
	Poly operator += (const Poly &t) {(*this)=(*this)+t;return *this;}
	Poly operator -= (const Poly &t) {(*this)=(*this)-t;return *this;}
	Poly operator *= (const Poly &t) {(*this)=(*this)*t;return *this;}
	Poly operator *= (int t) {for(auto &i:a) i=mod(1ll*i*t);return (*this);}
	Poly inv(int n)
	{
		if(a.size()<n) a.resize(n);if(n==1) return Poly({qpow(a[0],MOD-2)});
		Poly t=inv((n+1)/2),t1(vector<int>(a.begin(),a.begin()+n));
		init(n*2-1);t.NTT(0);t1.NTT(0);
		for(int i=0;i<lim;++i) t.a[i]=mod((2-mod(1ll*t.a[i]*t1.a[i])+MOD)*t.a[i]);
		t.NTT(1);t.a.resize(n);return t;
	}
	void deriv() {if(!a.empty()) {for(int i=1;i<a.size();++i) a[i-1]=mod(1ll*a[i]*i);a.po();}}
}f,f1;
int n,m,ans;
int main()
{
	MOD=998244353;FM=FastMod(MOD);initg();
    scanf("%d %d",&n,&m);ans=1;init1(1e6);

    f.a.resize(n);f1.a.resize(m);
    for(int i=0;i<n;++i) f.a[i]=mod(1ll*invfc[i]*invfc[i]);
    for(int i=0;i<m;++i) f1.a[i]=mod(1ll*invfc[i]*invfc[i]);
    f*=f1;
    for(int i=0;i<f.a.size();++i) W(ans,mod(1ll*f.a[i]*fc[i])*fc[i]);
    
    f.a.resize(n);f1.a.resize(m);
    for(int i=0;i<n;++i) f.a[i]=mod(1ll*invfc[i+1]*invfc[i-1]);
    for(int i=0;i<m;++i) f1.a[i]=mod(1ll*invfc[i+1]*invfc[i-1]);
    f*=f1;
    for(int i=0;i<f.a.size();++i) W(ans,mod(1ll*(MOD-f.a[i])*fc[i])*fc[i]);

    ans=mod(ans*2);
    W(ans,MOD-calc(n,m));

    for(int i=1;i<n;++i) W(ans,1ll*calc(i,m)*(n-i-1));
    for(int i=1;i<m;++i) W(ans,1ll*calc(n,i)*(m-i-1));
    printf("%d\n",ans);return 0;
}