/*
* Author: Enucai
* Date: 2022-12-14 08:47:28
* LastEditTime: 2023-05-04 11:32:03
*/

#include <bits/stdc++.h>
#include <sys/time.h>
#ifdef dbg
#define D(...) fprintf(stderr, __VA_ARGS__)
#define DD(...) D(#__VA_ARGS__ " = "), debug_helper::debug(__VA_ARGS__), D("\n")
#include "C:\Users\wsyear\Desktop\OI\templates\debug.hpp"
#else
#define D(...) ((void)0)
#define DD(...) ((void)0)
#endif
#define rep(i, j, k) for (int i = (j); i <= (k); ++i)
#define per(i, j, k) for (int i = (j); i >= (k); --i)
#define SZ(v) int((v).size())
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second
#define gc getchar
#define pc putchar
using ll = long long;
using pii = std::pair<int, int>;
using pll = std::pair<ll, ll>;

using namespace std;

template <class T = int> T read() {
  T x = 0; bool f = 0; char ch = gc();
  while (!isdigit(ch)) f = ch == '-', ch = gc();
  while (isdigit(ch)) x = (x << 3) + (x << 1) + (ch ^ 48), ch = gc();
  return f ? -x: x;
}
template <class T> void write(T x) {
  if (x >= 0) { if (x > 9) write(x / 10); pc(x % 10 + 48); }
  else { pc('-'); if (x < -9) write(-x / 10); pc(48 - x % 10); }
}

template <int P>
class mod_int {
  using Z = mod_int;

private:
  static int mo(int x) { return x < 0 ? x + P : x; }

public:
  int x;
  int val() const { return x; }
  mod_int() : x(0) {}
  template <class T>
  mod_int(const T &x_) : x(x_ >= 0 && x_ < P ? static_cast<int>(x_) : mo(static_cast<int>(x_ % P))) {}
  bool operator==(const Z &rhs) const { return x == rhs.x; }
  bool operator!=(const Z &rhs) const { return x != rhs.x; }
  Z operator-() const { return Z(x ? P - x : 0); }
  Z pow(long long k) const {
    Z res = 1, t = *this;
    while (k) {
      if (k & 1) res *= t;
      if (k >>= 1) t *= t;
    }
    return res;
  }
  Z &operator++() {
    x < P - 1 ? ++x : x = 0;
    return *this;
  }
  Z &operator--() {
    x ? --x : x = P - 1;
    return *this;
  }
  Z operator++(int) {
    Z ret = x;
    x < P - 1 ? ++x : x = 0;
    return ret;
  }
  Z operator--(int) {
    Z ret = x;
    x ? --x : x = P - 1;
    return ret;
  }
  Z inv() const { return pow(P - 2); }
  Z &operator+=(const Z &rhs) {
    (x += rhs.x) >= P && (x -= P);
    return *this;
  }
  Z &operator-=(const Z &rhs) {
    (x -= rhs.x) < 0 && (x += P);
    return *this;
  }
  Z &operator*=(const Z &rhs) {
    x = 1ULL * x * rhs.x % P;
    return *this;
  }
  Z &operator/=(const Z &rhs) { return *this *= rhs.inv(); }
#define setO(T, o)                                 \
  friend T operator o(const Z &lhs, const Z &rhs) {\
    Z res = lhs;                                   \
    return res o## = rhs;                          \
  }
  setO(Z, +) setO(Z, -) setO(Z, *) setO(Z, /)
#undef setO
};
const int P = 998244353;
using Z = mod_int<P>;

namespace Poly_space {
std::vector<int> rev;
std::vector<Z> roots{0, 1};
void dft(std::vector<Z> &a) {
  int n = a.size();
  if (int(rev.size()) != n) {
    int k = __builtin_ctz(n) - 1;
    rev.resize(n);
    for (int i = 0; i < n; i++) {
      rev[i] = rev[i >> 1] >> 1 | (i & 1 ? 1 << k : 0);
    }
  }
  for (int i = 0; i < n; i++)
    if (rev[i] < i) std::swap(a[i], a[rev[i]]);
  if (int(roots.size()) < n) {
    int k = __builtin_ctz(roots.size());
    roots.resize(n);
    while ((1 << k) < n) {
      Z e = Z(3).pow((P - 1) >> (k + 1));
      for (int i = 1 << (k - 1); i < (1 << k); i++)
        roots[2 * i] = roots[i], roots[2 * i + 1] = roots[i] * e;
      k++;
    }
  }
  for (int k = 1; k < n; k *= 2)
    for (int i = 0; i < n; i += 2 * k)
      for (int j = 0; j < k; j++) {
        Z u = a[i + j], v = a[i + j + k] * roots[k + j];
        a[i + j] = u + v, a[i + j + k] = u - v;
      }
}
void idft(std::vector<Z> &a) {
  int n = a.size();
  std::reverse(a.begin() + 1, a.end());
  dft(a);
  Z inv = (1 - P) / n;
  for (int i = 0; i < n; i++) a[i] *= inv;
}
struct Poly {
  std::vector<Z> a;
  Poly() {}
  Poly(const std::vector<Z> &a) : a(a) {}
  Poly(const std::initializer_list<Z> &a) : a(a) {}
  int size() const { return a.size(); }
  void resize(int n) { a.resize(n); }
  Z operator[](int idx) const {
    if (idx < 0 || idx >= size()) return 0;
    return a[idx];
  }
  Z &operator[](int idx) { return a[idx]; }
  Poly mulxk(int k) const {
    auto b = a;
    b.insert(b.begin(), k, 0);
    return Poly(b);
  }
  Poly modxk(int k) const {
    k = std::min(k, size());
    return Poly(std::vector<Z>(a.begin(), a.begin() + k));
  }
  Poly divxk(int k) const {
    if (size() <= k) return Poly();
    return Poly(std::vector<Z>(a.begin() + k, a.end()));
  }
  friend Poly operator+(const Poly &a, const Poly &b) {
    std::vector<Z> res(std::max(a.size(), b.size()));
    for (int i = 0; i < int(res.size()); i++) res[i] = a[i] + b[i];
    return Poly(res);
  }
  friend Poly operator-(const Poly &a, const Poly &b) {
    std::vector<Z> res(std::max(a.size(), b.size()));
    for (int i = 0; i < int(res.size()); i++) res[i] = a[i] - b[i];
    return Poly(res);
  }
  friend Poly operator*(Poly a, Poly b) {
    if (a.size() == 0 || b.size() == 0) return Poly();
    int sz = 1, tot = a.size() + b.size() - 1;
    while (sz < tot) sz *= 2;
    a.a.resize(sz), b.a.resize(sz), dft(a.a), dft(b.a);
    for (int i = 0; i < sz; ++i) a.a[i] = a[i] * b[i];
    idft(a.a), a.resize(tot);
    return a;
  }
  friend Poly operator*(Z a, Poly b) {
    for (int i = 0; i < int(b.size()); i++) b[i] *= a;
    return b;
  }
  friend Poly operator*(Poly a, Z b) {
    for (int i = 0; i < int(a.size()); i++) a[i] *= b;
    return a;
  }
  Poly &operator+=(Poly b) { return (*this) = (*this) + b; }
  Poly &operator-=(Poly b) { return (*this) = (*this) - b; }
  Poly &operator*=(Poly b) { return (*this) = (*this) * b; }
  Poly deriv() const {
    if (a.empty()) return Poly();
    std::vector<Z> res(size() - 1);
    for (int i = 0; i < size() - 1; ++i) res[i] = (i + 1) * a[i + 1];
    return Poly(res);
  }
  Poly integr() const {
    std::vector<Z> res(size() + 1);
    for (int i = 0; i < size(); ++i) res[i + 1] = a[i] / (i + 1);
    return Poly(res);
  }
  Poly inv(int m) const {
    Poly x{a[0].inv()};
    int k = 1;
    while (k < m) k *= 2, x = (x * (Poly{2} - modxk(k) * x)).modxk(k);
    return x.modxk(m);
  }
  Poly log(int m) const {
    return (deriv() * inv(m)).integr().modxk(m);
  }
  Poly exp(int m) const {
    Poly x{1};
    int k = 1;
    while (k < m) k *= 2, x = (x * (Poly{1} - x.log(k) + modxk(k))).modxk(k);
    return x.modxk(m);
  }
  Poly sqrt(int m) const {
    Poly x{1};
    int k = 1;
    while (k < m) k *= 2, x = (x + (modxk(k) * x.inv(k)).modxk(k)) * ((P + 1) / 2);
    return x.modxk(m);
  }
  Poly mulT(Poly b) const {
    if (b.size() == 0) return Poly();
    int n = b.size();
    std::reverse(b.a.begin(), b.a.end());
    return ((*this) * b).divxk(n - 1);
  }
  std::vector<Z> eval(std::vector<Z> x) const {
    if (size() == 0) return std::vector<Z>(x.size(), 0);
    const int n = std::max(int(x.size()), size());
    std::vector<Poly> q(4 * n);
    std::vector<Z> ans(x.size());
    x.resize(n);
    std::function<void(int, int, int)> build = [&](int p, int l, int r) {
      if (r - l == 1) q[p] = Poly{1, -x[l]};
      else {
        int m = (l + r) / 2;
        build(2 * p, l, m), build(2 * p + 1, m, r);
        q[p] = q[2 * p] * q[2 * p + 1];
      }
    };
    build(1, 0, n);
    std::function<void(int, int, int, const Poly &)> work = [&](int p, int l, int r, const Poly &num) {
    if (r - l == 1) {
      if (l < int(ans.size())) ans[l] = num[0];
    } else {
      int m = (l + r) / 2;
      work(2 * p, l, m, num.mulT(q[2 * p + 1]).modxk(m - l));
      work(2 * p + 1, m, r, num.mulT(q[2 * p]).modxk(r - m));
    }
    };
    work(1, 0, n, mulT(q[1].inv(n)));
    return ans;
  }
};
}

using namespace Poly_space;
const int N = 1000010;

int n, m;
Z fac[N], ivf[N];

Z binom(int x, int y) {
  if (x < 0 || y < 0 || x < y) return 0;
  return fac[x] * ivf[y] * ivf[x - y];
}

int main() {
  n = read(), m = read();
  fac[0] = 1;
  rep (i, 1, n * m) fac[i] = fac[i - 1] * i;
  ivf[n * m] = fac[n * m].inv();
  per (i, n * m, 1) ivf[i - 1] = ivf[i] * i;
  Poly F; F.resize(m + 1);
  rep (i, 0, m) F[i] = binom(m, i) * binom(m, i) * fac[i];
  rep (i, 0, m) if (i & 1) F[i] = -F[i];
  int sz = 1;
  F = F.log(n * m + 1);
  rep (i, 0, n * m) F[i] *= n;
  F = F.exp(n * m + 1);
  Z ans = 0;
  rep (i, 0, n * m) ans += F[i] * fac[n * m - i];
  write(ans.val());
}