// #include <atcoder/all>
// using namespace atcoder;
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for (int i = 0; i < (n); i++)
#define all(x) (x).begin(), (x).end()
#define popcnt(x) __builtin_popcount(x)
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vll = vector<ll>;
using vvi = vector<vector<int>>;
using vvll = vector<vector<ll>>;
const int inf = 1e9;
const ll lim = 1e18;
int dx[] = {1, 1, 0, -1, -1, -1, 0, 1};
int dy[] = {0, 1, 1, 1, 0, -1, -1, -1};

// const int mod = 1000000007;
const int mod = 998244353;
struct mint {
  ll x;  // typedef long long ll;
  mint(ll x = 0) : x((x % mod + mod) % mod) {}
  mint operator-() const { return mint(-x); }
  mint& operator+=(const mint a) {
    if ((x += a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator-=(const mint a) {
    if ((x += mod - a.x) >= mod) x -= mod;
    return *this;
  }
  mint& operator*=(const mint a) {
    (x *= a.x) %= mod;
    return *this;
  }
  mint operator+(const mint a) const { return mint(*this) += a; }
  mint operator-(const mint a) const { return mint(*this) -= a; }
  mint operator*(const mint a) const { return mint(*this) *= a; }
  mint pow(ll t) const {
    if (!t) return 1;
    mint a = pow(t >> 1);
    a *= a;
    if (t & 1) a *= *this;
    return a;
  }

  // for prime mod
  mint inv() const { return pow(mod - 2); }
  mint& operator/=(const mint a) { return *this *= a.inv(); }
  mint operator/(const mint a) const { return mint(*this) /= a; }
};
istream& operator>>(istream& is, mint& a) { return is >> a.x; }
ostream& operator<<(ostream& os, const mint& a) { return os << a.x; }

template <typename T>
struct BinaryIndexedTree {
  vector<T> data;

  BinaryIndexedTree(int sz) { data.assign(++sz, 0); }

  T sum(int i) {
    T ret = 0;
    for (++i; i > 0; i -= i & -i) ret += data[i];
    return (ret);
  }

  void add(int i, T x) {
    for (++i; i < data.size(); i += i & -i) data[i] += x;
  }
};

mint modpow(mint b, int e) {
  mint res = 1;
  while (e) {
    if (e & 1) res *= b;
    b = b * b;
    e >>= 1;
  }
  return res;
}

int main() {
  cin.tie(0);
  ios::sync_with_stdio(false);

  int n, m;
  cin>>n>>m;
  vector bits(m + 1, BinaryIndexedTree<mint>(n + 1));
  BinaryIndexedTree<mint> dp(n + 1);

  dp.add(0, 1);
  rep(i, n) for (int a = 1; a <= m; a++) {
    mint val =
        dp.sum(i) - dp.sum(i + 1 - a) - bits[a].sum(i) + bits[a].sum(i + 1 - a);
    bits[a].add(i + 1, val);
    dp.add(i + 1, val);
  }

  mint ans = modpow(mint(m), n) - dp.sum(n) + dp.sum(n - 1);
  cout<<ans<<endl;

  return 0;
}