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

using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
#define rep3(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define rep2(i, a, b) rep3(i, a, b, 1)
#define rep1(i, n) rep2(i, 0, n)
#define rep0(n) rep1(aaaaa, n)
#define ov4(a, b, c, d, name, ...) name
#define rep(...) ov4(__VA_ARGS__, rep3, rep2, rep1, rep0)(__VA_ARGS__)
#define per(i, a, b) for (ll i = (a) - 1; i >= (b); i--)
#define fore(e, v) for (auto&& e : v)
#define all(a) begin(a), end(a)
#define sz(a) (int)(size(a))
#define lb(v, x) (lower_bound(all(v), x) - begin(v))
#define eb emplace_back

template <typename T, typename S>
bool chmin(T& a, const S& b) {
  return a > b ? a = b, 1 : 0;
}
template <typename T, typename S>
bool chmax(T& a, const S& b) {
  return a < b ? a = b, 1 : 0;
}
const int INF = 1e9 + 100;
const ll INFL = 3e18 + 100;
#define i128 __int128_t
struct _ {
  _() { cin.tie(0)->sync_with_stdio(0), cout.tie(0); }
} __;

const int MOD=998244353;

ll modpow(ll a,ll n){
  long long ret=1%MOD,t=a%MOD;
  while(n>0){
    if(n&1)ret=ret*t%MOD;
    t=t*t%MOD;
    n/=2;
  }
  return ret;
}

void ch(ll &a,ll b){
  a=(a+b)%MOD;
}

int main(){
  int N,M;
  cin>>N>>M;
  ll ans=0,pM=modpow(M,N),invM=modpow(M,MOD-2);
  rep(i,M){
    ll c=(M-i)*invM%MOD;
    if(c==1){
      ch(ans,pM*N);
    }else{
      ch(ans,(modpow(c,N)-1)*modpow(c-1,MOD-2)%MOD*c%MOD*pM);
    }
  }
  cout<<ans<<'\n';
}