//#define _GLIBCXX_DEBUG
#include <bits/stdc++.h>
using namespace std;
#define rep(i, n) for(int i=0; i<n; ++i)
#define all(v) v.begin(), v.end()
#define rall(v) v.rbegin(), v.rend()
using ll = int64_t;
using ull = uint64_t;
using ld = long double;
using P = pair<int, int>;
using vs = vector<string>;
using vi = vector<int>;
using vvi = vector<vi>;
template<class T> using PQ = priority_queue<T>;
template<class T> using PQG = priority_queue<T, vector<T>, greater<T>>;
const int INF = 0xccccccc;
const ll LINF = 0xcccccccccccccccLL;
template<typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {return a < b && (a = b, true);}
template<typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {return a > b && (a = b, true);}
template<typename T1, typename T2>
istream &operator>>(istream &is, pair<T1, T2> &p) { return is >> p.first >> p.second;}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) { return os << p.first << ' ' << p.second;}

//const unsigned int mod = 1000000007;
const unsigned int mod = 998244353;

struct mint {
  unsigned int x;
  mint():x(0) {}
  mint(int64_t x_) {
    int64_t v = int64_t(x_ % mod);
    if(v < 0) v += mod;
    x = (unsigned int)v;
  }
  static mint row(int v) {
    mint v_;
    v_.x = v;
    return v_;
  }
  mint operator-() const { return row(x?mod-x:0);}
  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) {
    uint64_t z = x;
    z *= a.x;
    x = (unsigned int)(z % 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;}
  friend bool operator==(const mint &a, const mint &b) {return a.x == b.x;}
  friend bool operator!=(const mint &a, const mint &b) {return a.x != b.x;}
  mint &operator++() {
    x++;
    if(x == mod) x = 0;
    return *this;
  }
  mint &operator--() {
    if(x == 0) x = mod;
    x--;
    return *this;
  }
  mint operator++(int) {
    mint result = *this;
    ++*this;
    return result;
  }
  mint operator--(int) {
    mint result = *this;
    --*this;
    return result;
  }
  mint pow(int64_t t) const {
    mint x_ = *this, r = 1;
    while(t) {
      if(t&1) r *= x_;
      x_ *= x_;
      t >>= 1;
    }
    return r;
  }
  //for prime mod
  mint inv() const { return pow(mod-2);}
  mint& operator/=(const mint a) { return *this *= a.inv();}
  mint operator/(const mint a) {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;}

string to_string(mint a) {
  return to_string(a.x);
}

//head


int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  if(n == 1) {
    cout << m << endl;
    return 0;
  }
  mint ans, _ = mint(m).inv();
  vector<mint> _r(m+1), r(m, mint(1));
  for(int j = 1; j < m+1; j++) _r[j] = (-_*j).inv();
  for(int i = 1; i < n; i++) {
    for(int j = 1; j < m+1; j++) {
      r[j-1] *= -_*j+1;
      ans += (r[j-1]-1)*_r[j];
    }
  }
  cout << mint(m).pow(n)*n - ans*mint(m).pow(n-2) << endl;
}
#include <bits/stdc++.h>

using namespace std;
typedef long long LL;
typedef pair<int, int> pii;

const int MOD = 998244353;
int quick_pow(int a,int x) {
    int ret = 1;
    while(x) {
        if (x & 1) {
            ret = 1LL * ret * a % MOD;
        }
        x >>= 1;
        a = 1LL * a * a % MOD;
    }
    return ret;
}
int N, M;
int q[5010][5010];

int main() {
    scanf("%d%d",&N,&M);
    for (int i=0;i<=M;i++) {
        for (int j=0;j<=N;j++) {
            q[i][j] = quick_pow(i, j);
        }
    }
    LL ans = 1LL * q[M][N] * N % MOD;
    for (int i=1;i<=M;i++) {
        for (int len=2;len<=N;len++) {
            LL pos = N - len + 1;
            LL in = q[M - i][len - 2];
            LL out = q[M][N - len];
            ans = (ans + MOD - pos * in % MOD * out % MOD) % MOD;
        }
    } 
    printf("%lld\n",ans);
}