#include <bits/stdc++.h>
using namespace std;
#define MOD 1000000007
#define MOD2 998244353
#define rep(i,n) for (long long i = 0; i < (long long)(n); i++)
#define reps(i,s,n) for (long long i = (long long)(s); i < (long long)(n); i++)
#define pr(a) cout << a
#define prl(a) cout << (a) << endl
#define prld(a) cout << setprecision(15)<< (a) << endl 
#define allrange(a) a.begin(),a.end()

long long mypow(long long x, long long n) {
    long long ret = 1;
    while (n > 0) {
        if (n & 1) ret = ret * x % MOD2;  // n の最下位bitが 1 ならば x^(2^i) をかける
        x = x * x % MOD2;
        n >>= 1;  // n を1bit 左にずらす
    }
    return ret;
}

long long sum(long long s,long long t){
    return (((t-s+1)*(t+s))/2)%MOD2;
}


long long getsum(long long s,long long t,long long n){
    long long a = sum(s,t);
    long long b = mypow((t-s+1),n-1);
    
    return (((a*b)%MOD2)*n)%MOD2;
}

void solve(long long N, long long M){
    long long n= N%MOD2;

    long long X1 = getsum(1,M,n);
    X1 = (X1*M)%MOD2;
    long long X2 = 0;
    rep(i,M){
        long long buf = getsum(i+1,M,n);
        X2 = (X2+buf)%MOD2;
    }
    X2 = MOD2-X2;
    
    long long X3 = 0;
    rep(i,M-1){
        long long buf = getsum(1,i+1,n);
        X3 = (X3+buf)%MOD2;
    }
    X3 = MOD2-X3;
    long long ans = (X1+X2+X3)%MOD2;
    prl(ans);
}


int main(){
    std::cin.tie(0); // cinとcoutの同期を解除
    std::ios::sync_with_stdio(false);
    //1変数入力
    long long  N,M;
    cin >> N >> M;
 
    solve(N,M);
}