#include<iostream>

using namespace std;
using ll=long long;

ll pow_mod(ll a, ll n, ll mod){
    if (n==0) return 1;
    else if (n&1) return (a*pow_mod(a,n-1,mod)%mod);
    else{
        ll b=pow_mod(a,n/2,mod);
        return b*b%mod;
    }
}

int main(){
    ll N, M;
    cin >> N >> M;
    
    ll Mod=998244353;
    ll X=pow_mod(M,N,Mod)*(M+1)%Mod;
    ll Y=0;

    for (int l=1; l<=M; l++) Y+=pow_mod(l,N,Mod);
    
    ll Z=(X-2*Y)%Mod; Z+=Mod; Z%=Mod;

    ll two_inv=pow_mod(2,Mod-2,Mod);
    
    N%=Mod;
    ll k=(N*two_inv)%Mod; k=(k*(M+1))%Mod;

    Z*=k; Z%=Mod;
    cout << Z << endl;
}