#include <bits/stdc++.h>
using namespace std;
#include <atcoder/all>
using namespace atcoder;
using mint = atcoder::static_modint<998244353>;
// using mint = atcoder::static_modint<1000000007>;
using ld = long double;
using ll = long long;
#define mp(a,b) make_pair(a,b)
#define rep(i,s,n) for(int i=s; i<(int)n; i++)
using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vvvvl = vector<vvvl>;
const vector<int> dx{1,0,-1,0},dy{0,1,0,-1};

int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    int n,m;cin >> n >> m;
    mint ans=mint(m).pow(n)*n;
    rep(i,2,m+1){
        mint c=mint(m)/(m+1-i);
        ans+=(mint(c).pow(n)-1)/(c-1)*mint(m+1-i).pow(n);
    }
    cout << ans.val();
}