// Templates and Snippets -> https://github.com/igeeeeee/template
#ifdef ONLINE_JUDGE
#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#endif
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
using i128 = __int128_t;
using u128 = __uint128_t;
ostream& operator<<(ostream& os, u128 x) {if (x >= 10) os << x / 10;return os << char('0' + x % 10);}
ostream& operator<<(ostream& os, i128 x){if (x < 0){os << '-';return os << (-(u128)x);}return os << (u128)x;}
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define rrep(i,start,end) for (ll i = start;i >= (ll)(end);i--)
#define repn(i,end) for(ll i = 0; i <= (ll)(end); i++)
#define reps(i,start,end) for(ll i = start; i < (ll)(end); i++)
#define repsn(i,start,end) for(ll i = start; i <= (ll)(end); i++)
#define each(p,a) for(auto &p:a)
typedef vector<ll> vll;
typedef vector<pair<ll ,ll>> vpll;
typedef vector<vector<pair<ll ,ll>>> vvpll;
typedef vector<vector<ll>> vvll;
typedef vector<vector<vector<ll>>> vvvll;
typedef pair<ll ,ll> pll;
typedef pair<ull,ull> pull;
typedef tuple<ll , ll , ll> tpl3;
typedef tuple<ll , ll , ll , ll> tpl4;
typedef tuple<ll , ll , ll , ll , ll> tpl5;
typedef tuple<ll , ll , ll , ll , ll , ll> tpl6;
#define FI first
#define SE second
#define LL(...) ll __VA_ARGS__; input(__VA_ARGS__)
#define LD(...) ld __VA_ARGS__; input(__VA_ARGS__)
#define Str(...) string __VA_ARGS__; input(__VA_ARGS__)
#define Ch(...) char __VA_ARGS__; input(__VA_ARGS__)
#define all(a)  (a).begin(),(a).end()
#define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() );
#define sz(x) (ll)x.size()
// << std::fixed << std::setprecision(10)
const ll INF = 1LL << 60;
const ld EPS = 1e-9;
 
ll lceil(ll a,ll b){if(a%b==0){return a/b;}if(a>=0){return (a/b)+1;}else{return -((-a)/b);}}
ll lfloor(ll a,ll b){if(a%b==0){return a/b;}if(a>=0){return (a/b);}else{return -((-a)/b)-1;}}
inline ll positive_mod(ll a,ll m){return (a % m + m)%m;}
inline ll popcnt(ull a){ return __builtin_popcountll(a);}
//0indexed
inline ll topbit(ll a){assert(a != 0);return 63 - __builtin_clzll(a);}
inline ll smlbit(ll a){assert(a != 0);return __builtin_ctzll(a);}
template<class T> bool chmin(T& a, T b){if(a > b){a = b;return true;}return false;}
template<class T> bool chmax(T& a, T b){if(a < b){a = b;return true;}return false;}
template<typename T> std::istream &operator>>(std::istream&is,std::vector<T>&v){for(T &in:v){is>>in;}return is;}
template<typename T> std::ostream &operator<<(std::ostream&os,const std::vector<T>&v){for(auto it=std::begin(v);it!=std::end(v);){os<<*it<<((++it)!=std::end(v)?" ":"");}return os;}
template<typename T1, typename T2>std::ostream &operator<< (std::ostream &os, std::pair<T1,T2> p){os << "{" << p.first << "," << p.second << "}";return os;}
template<class... T>void input(T&... a){(cin >> ... >> a);}
void print(){cout << endl;}
template<class T, class... Ts>void print(const T& a, const Ts&... b){cout << a;((cout << ' ' << b), ...);cout << endl;}
template<class T> void pspace(const T& a){ cout << a << ' ';}
void perr(){cerr << endl;}
template<class T, class... Ts>void perr(const T& a, const Ts&... b){cerr << a;((cerr << ' ' << b), ...);cerr << endl;}
void yes(bool i = true){ return print(i?"yes":"no"); }
void Yes(bool i = true){ return print(i?"Yes":"No"); }
void YES(bool i = true){ return print(i?"YES":"NO"); }
template <class T> vector<T> &operator++(vector<T> &v) {for(auto &e : v) e++;return v;}
template <class T> vector<T> operator++(vector<T> &v, signed) {auto res = v;for(auto &e : v) e++;return res;}
template <class T> vector<T> &operator--(vector<T> &v) {for(auto &e : v) e--;return v;}
template <class T> vector<T> operator--(vector<T> &v, signed) {auto res = v;for(auto &e : v) e--;return res;}
//grid探索用
vector<ll> _ta = {0,0,1,-1,1,1,-1,-1};
vector<ll> _yo = {1,-1,0,0,1,-1,1,-1};
bool isin(ll now_i,ll now_j,ll h,ll w){return (0<=now_i && now_i < h && 0 <= now_j && now_j < w);}
  
ll lpow(ll x,ll n){ll ans = 1;while(n >0){if(n & 1)ans *= x;x *= x;n >>= 1;}return ans;}
ll Modlpow(ll x,ll n,ll m){ll ans = 1;ll a = x%m;while(n >0){if(n & 1){ans *= a;ans%= m;}a *= a;a %= m;n >>= 1;}return ans;} 
const ll MOD9 = 998244353LL;
const ll MOD10 = 1000000007LL;

void solve();
#ifdef DEBUG
void naive();
string run(void (*f)(), const string& input) {istringstream iss(input);ostringstream oss;auto* cinbuf = cin.rdbuf(iss.rdbuf());auto* coutbuf = cout.rdbuf(oss.rdbuf());cin.clear();f();cout.flush();cin.rdbuf(cinbuf);cout.rdbuf(coutbuf);cin.clear();return oss.str();}

bool check(const string& input) {
  string ans = run(solve, input);istringstream acin(ans);
  string correct = run(naive, input);istringstream ccin(correct);
  // ll x;acin >> x;とかで使える(構築とかの確認用)

  if (ans == correct) return true;//末尾の空白まで完全一致

  cerr << "========== INPUT ==========\n";
  cerr << input;
  cerr << "========== EXPECTED =======\n";
  cerr << correct;
  cerr << "========== ACTUAL =========\n";
  cerr << ans;
  cerr << "===========================\n";
  return false;
}

uint64_t seed = chrono::steady_clock::now().time_since_epoch().count();
mt19937_64 rng(seed);
ll rnd(ll l, ll r){// l 以上 r 以下
  return uniform_int_distribution<ll>(l, r)(rng);
}

void test(){
  repsn(i,1,8){
    repsn(j,1,8){
      string input = to_string(i)+" "+to_string(j)+'\n';
      string ret = run(naive,input);
      istringstream ccin(ret);
      ll a;ccin >> a;
      cout << a <<" " ;
    }
    cout << endl;
  }
  // rep(tc,100000){
  //   // ----- テストケース生成(文字列で!!) -----
  //   string input;
  //   ll n = rnd(1,5);
  //   input += to_string(n);
  //   input += ' ';
  //   ll m = rnd(1,5);
  //   input += to_string(m);
  //   input += '\n';
  //   // ----- 比較 -----
  //   // check(input);
  //   cout << input << endl;
  //   string correct = run(naive, input);
  //   cout << correct << endl;
  //   cout <<"-------" << endl;

  //   if ((tc+1) % 1000 == 0) {
  //     cerr << tc+1 << " cases passed\n";
  //   }
  // }
}

void naive(){//cinで受け取りcoutで出力でよい
  LL(n,m);
  ll cnt = 0;
  auto dfs = [&](auto dfs, vll  v)->void {
    if(sz(v)==n){
      vll sum(n+1);
      rep(i,n)sum[i+1] = sum[i]+v[i];
      reps(i,1,n){
        if(sum[i]*2==sum.back()){
          // cout << v << endl;
          cnt++;
        }
      }
      return ;
    }
    repsn(i,1,m){
      v.push_back(i);
      dfs(dfs,v);
      v.pop_back();
    }
  };
  vll v;
  dfs(dfs,v);
  cout << cnt << endl;
}
#endif

//ref https://github.com/atcoder/live_library/blob/master/mat.cpp
template<typename T>
struct Matrix {
  int h, w;
  vector<vector<T>> d;
  Matrix() {}
  Matrix(int h, int w, T val=0): h(h), w(w), d(h, vector<T>(w,val)) {}
  Matrix& unit() {
    assert(h == w);
    rep(i,h) d[i][i] = 1;
    return *this;
  }
  const vector<T>& operator[](int i) const { return d[i];}
  vector<T>& operator[](int i) { return d[i];}
  Matrix operator*(const Matrix& a) const {
    assert(w == a.h);
    Matrix r(h, a.w);
    rep(i,h)rep(k,w)rep(j,a.w) {
      r[i][j] += d[i][k]*a[k][j];
    }
    return r;
  }
  Matrix pow(long long t) const {
    assert(h == w);
    if (!t) return Matrix(h,h).unit();
    if (t == 1) return *this;
    Matrix r = pow(t>>1);
    r = r*r;
    if (t&1) r = r*(*this);
    return r;
  }
  /* mint only
  mint det() {
    assert(h == w);
    mint res = 1;
    rep(k,h) {
      for (int i = k; i < h; ++i) {
        if (d[i][k] == 0) continue;
        if (i != k) {
          swap(d[i],d[k]);
          res = -res;
        }
      }
      if (d[k][k] == 0) return 0;
      res *= d[k][k];
      mint inv = mint(1)/d[k][k];
      rep(j,h) d[k][j] *= inv;
      for (int i = k+1; i < h; ++i) {
        mint c = d[i][k];
        for (int j = k; j < h; ++j) d[i][j] -= d[k][j]*c;
      }
    }
    return res;
  }
  //*/
};
using mint = modint998244353;
void solve(){
  LL(n,m);
  if(n==1){
    cout << 0 << endl;
    return ;
  }
  Matrix<mint> x(1,2),a(2,2);
  x[0][0] = m;
  x[0][1] = 0;
  a[0][0] = m-1;
  a[0][1] = 1;
  a[1][0] = m;
  x = x * a.pow(n-2);
  cout << x[0][0].val() << endl;
}
 
int main(){
  ios::sync_with_stdio(false);cin.tie(nullptr);
  #ifdef DEBUG
    test();
  #else
    solve();
  #endif
}