#include<bits/stdc++.h>
using namespace std;

#define int long long
#define F first 
#define S second
#define pb push_back

const int mol=998244353;

int p[1000005], fac[1000005], inv[1000005];

int ff(int g, int h){
    int bas=g, ans=1;
    while(h) {
        if(h&1) ans*=bas, ans%=mol;
        bas*=bas, bas%=mol;
        h>>=1;
    }
    return ans;
}
int C(int g, int h){
    return fac[g]*inv[h]%mol*inv[g-h]%mol;
}

void solve(){
    int n, m;
    cin>>n>>m;

    int ans=1;
    p[0]=1, fac[0]=1;
    for(int i=1;i<=n;i++) ans*=m, ans%=mol;
    int q=ans;
    for(int i=1;i<=n;i++) p[i]=p[i-1]*(m-1)%mol, fac[i]=fac[i-1]*i%mol;
    inv[n]=ff(fac[n], mol-2);
    
    for(int i=n-1;i>=0;i--) inv[i]=inv[i+1]*(i+1)%mol;

    for(int i=1;i<m;i++){
        ans+=(ff(m, n)-ff(i, n)+mol)*2, ans%=mol;
    }
    // ans-=q*2, ans%=mol, ans=(ans+mol)%mol;
    

    cout<<ans<<"\n";
}

signed main(){
    ios::sync_with_stdio(0);cin.tie(0);
    // int t;
    // cin>>t;
    // while(t--)
    solve();
    return 0;
}