// g++-13 2.cpp -std=c++20 -O2 -I .
#include <bits/stdc++.h>
using namespace std;

#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

#include<ext/pb_ds/assoc_container.hpp>
#include<ext/pb_ds/tree_policy.hpp>
#include<ext/pb_ds/tag_and_trait.hpp>
using namespace __gnu_pbds;

#include <atcoder/modint>
using namespace atcoder;

using ll = long long;
using ld = long double;
 
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using vld = vector<ld>;
using vvld = vector<vld>;
using vst = vector<string>;
using vvst = vector<vst>;

#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define pq_big(T) priority_queue<T,vector<T>,less<T>>
#define pq_small(T) priority_queue<T,vector<T>,greater<T>>
#define all(a) a.begin(),a.end()
#define rep(i,start,end) for(ll i=start;i<(ll)(end);i++)
#define per(i,start,end) for(ll i=start;i>=(ll)(end);i--)
#define uniq(a) sort(all(a));a.erase(unique(all(a)),a.end())

random_device seed;
mt19937_64 randint(seed());

ll grr(ll mi, ll ma) { // [mi, ma)
    return mi + randint() % (ma - mi);
}

using mint = modint998244353;

int main(){
  std::ios::sync_with_stdio(false);
  std::cin.tie(nullptr);

  int n,m;cin>>n>>m;
  mint ans=0;
  rep(v,1,m+1){
    // min >= v なる i の個数の期待値
    mint prob=m-v+1;
    prob/=m;
    // prob=1-prob;
    if(prob.val()==1){
      ans+=n;
      continue;
    }
    mint c=prob.pow(n);
    c=(1-c)/(1-prob);
    c*=prob;
    ans+=c;
  }
  rep(i,0,n){
    ans*=m;
  }
  cout<<ans.val()<<endl;
}