#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define fi first
#define se second
const ll mod=998244353;
typedef vector<ll> poly;
const int mb=20;//can change !!!!
ll roots[1<<mb];
int rev[1<<mb];
ll pw(ll x,ll y){
	if(y==0) return 1;
	if(y%2) return x*pw(x,y-1)%mod;
	ll res=pw(x,y/2);
	return res*res%mod;
}
void operator<<(ostream& out,poly y){
	for(auto c:y) out << c << ' ';
}
poly operator+(poly x,poly y){
	int n=max(x.size(),y.size());
	x.resize(n);y.resize(n);
	for(int i=0; i<n ;i++){
		x[i]+=y[i];
		if(x[i]>=mod) x[i]-=mod;
	}
	return x;
}
poly operator-(poly x,poly y){
	int n=max(x.size(),y.size());
	x.resize(n);y.resize(n);
	for(int i=0; i<n ;i++){
		x[i]+=mod-y[i];
		if(x[i]>=mod) x[i]-=mod;
	}
	return x;
}

void pre(){
	roots[0]=1;
	roots[1]=pw(15311432,1<<(23-mb));
	for(int i=1; i<(1<<mb) ;i++) roots[i]=roots[i-1]*roots[1]%mod;
}
void fft(poly &p){
	int n=p.size();
	roots[0]=1;
	int m=(1<<mb)/n;
	for(int i=1; i<n ;i++){
		rev[i]=rev[i/2]/2+((i&1)*n/2);
		if(i<rev[i]) swap(p[i],p[rev[i]]);
	}
	for(int k=1; k<n ;k*=2){
        for(int i=0; i<n ;i+=2*k){
            int cur=0,step=n/(2*k);
            for(int j=0; j<k;j++,cur+=step){
                ll x=p[i+j];
                ll y=p[i+j+k]*roots[cur*m]%mod;
                p[i+j]=(x+y>=mod?x+y-mod:x+y);
				p[i+j+k]=(x>=y?x-y:x+mod-y);
            }
        }
    }
}
poly operator*(poly x,poly y){
	int n=1;
	while(n<x.size()+y.size()-1) n*=2;
	x.resize(n,0);y.resize(n,0);
	fft(x);fft(y);
	for(int i=0; i<n ;i++) x[i]=x[i]*y[i]%mod;
	reverse(x.begin()+1,x.end());
	fft(x);
	ll inv=pw(n,mod-2);
	for(int i=0; i<n ;i++) x[i]=x[i]*inv%mod;
	while(x.size()>1 && x.back()==0) x.pop_back();
	return x;
}/*
vector<ll>multiply2(vector<ll>x,vector<ll>y){
	vector<ll>z;z.resize(x.size()+y.size()-1);
	for(auto c:z) c=0;
	for(int i=0; i<x.size() ;i++){
		for(int j=0; j<y.size() ;j++){
			z[i+j]=(z[i+j]+x[i]*y[j])%mod;	
		}
	}
	return z;
}*/
poly inverse(poly x){
	int n=1;
	poly g;g.resize(1);
	if(x[0]==1) g[0]=1;//:))
	else g[0]=pw(x[0],mod-2);
	while(n<x.size()){
		poly f0(n),g0(n),f1(n);
		if(x.size()<2*n) x.resize(2*n);
		for(int i=0; i<n ;i++){
			f0[i]=x[i];f1[i]=x[i+n];
			g0[i]=g[i];
		}
		auto tmp=poly{1}-(f0*g0);tmp.resize(2*n);
		for(int i=0; i<n ;i++) tmp[i]=tmp[i+n];
		tmp=tmp-(f1*g0);
		tmp.resize(n);
		tmp=tmp*g0;tmp.resize(n);
		g.resize(2*n);
		for(int i=0; i<n ;i++) g[i+n]=tmp[i];
		n*=2;
	}
	return g;
}
poly one = {1};
poly pw(poly x,ll y){
	if(y==0) return one;
	if(y%2) return x*pw(x,y-1);
	poly res=pw(x,y/2);
	return res*res;
}
//my code starts here
int n,m;
ll f[1000001],inf[1000001];
ll C(ll x,ll y){
	return f[x]*inf[x-y]%mod*inf[y]%mod;
}
int main(){
	ios::sync_with_stdio(false);cin.tie(0);
	pre();
	cin >> n >> m;
	f[0]=1;
	for(int i=1; i<=n*m ;i++) f[i]=i*f[i-1]%mod;
	inf[n*m]=pw(f[n*m],mod-2);
	for(int i=n*m; i>=1 ;i--) inf[i-1]=i*inf[i]%mod;
	poly g(m+1);
	for(int i=0; i<=m ;i++){
		g[i]=C(m,i)*inf[i]%mod;
		if((m-i)%2==1) g[i]=(mod-g[i])%mod;
	}
	g=pw(g,n);
	ll ans=0;
	for(int i=0; i<=n*m ;i++){
		//cout << g[i] << ' ';
		ans=(ans+g[i]*f[i])%mod;
	}
	//cout << endl;
	ans=ans*pw(f[m],n)%mod;
	cout << ans << '\n';
}