#include<bits/stdc++.h>
const int p = 998244353;
typedef long long LL;
using namespace std;
const int mod = p;

template<int mod>
struct ModInt {
#define T (*this)
    int x;
    ModInt() : x(0) {}
    ModInt(int y) : x(y >= 0 ? y : y + mod) {}
    ModInt(LL y) : x(y >= 0 ? y % mod : (mod - (-y) % mod) % mod) {}
    inline int inc(const int &v) {
        return v >= mod ? v - mod : v;
    }
    inline int dec(const int &v) {
        return v < 0 ? v + mod : v;
    }
    inline ModInt &operator+=(const ModInt &p) {
        x = inc(x + p.x);
        return T;
    }
    inline ModInt &operator-=(const ModInt &p) {
        x = dec(x - p.x);
        return T;
    }
    inline ModInt &operator*=(const ModInt &p) {
        x = (int)((LL)x * p.x % mod);
        return T;
    }
    inline ModInt inverse() const {
        int a = x, b = mod, u = 1, v = 0, t;
        while (b > 0)t = a / b, swap(a -= t * b, b), swap(u -= t * v, v);
        return u;
    }
    inline ModInt &operator/=(const ModInt &p) {
        T *= p.inverse();
        return T;
    }
    inline ModInt operator-() const {
        return -x;
    }
    inline friend ModInt operator+(const ModInt &lhs, const ModInt &rhs) {
        return ModInt(lhs) += rhs;
    }
    inline friend ModInt operator-(const ModInt &lhs, const ModInt &rhs) {
        return ModInt(lhs) -= rhs;
    }
    inline friend ModInt operator*(const ModInt &lhs, const ModInt &rhs) {
        return ModInt(lhs) *= rhs;
    }
    inline friend ModInt operator/(const ModInt &lhs, const ModInt &rhs) {
        return ModInt(lhs) /= rhs;
    }
    inline bool operator==(const ModInt &p) const {
        return x == p.x;
    }
    inline bool operator!=(const ModInt &p) const {
        return x != p.x;
    }
    ModInt qpow(LL n) const {
        ModInt ret(1), mul(x);
        while (n > 0) {
            if (n & 1)ret *= mul;
            mul *= mul, n >>= 1;
        }
        return ret;
    }
    inline friend ostream &operator<<(ostream &os, const ModInt &p) {
        return os << p.x;
    }
    inline friend istream &operator>>(istream &is, ModInt &a) {
        LL t;
        is >> t, a = ModInt<mod>(t);
        return is;
    }
    static int get_mod() {
        return mod;
    }
#undef T
};


using Z = ModInt<mod>;
namespace NTT {
    vector<int> rev;
    vector<Z> roots{0, 1};
    inline void dft(vector<Z> &a) {
        int n = (int)(a.size());
        if (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) << k;
        }
        for (int i = 0; i < n; i++)if (rev[i] < i)swap(a[i], a[rev[i]]);
        if (roots.size() < n) {
            int k = __builtin_ctz(roots.size());
            roots.resize(n);
            while ((1 << k) < n) {
                Z e = Z(3).qpow((mod - 1) >> (k + 1));
                for (int i = 1 << (k - 1); i < (1 << k); i++)
                    roots[i << 1] = roots[i], roots[i << 1 | 1] = roots[i] * e;
                k++;
            }
        }
        for (int k = 1; k < n; k <<= 1) {
            for (int i = 0; i < n; i += k << 1) {
                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;
                }
            }
        }
    }
    inline void idft(vector<Z> &a) {
        int n = (int)(a.size());
        reverse(a.begin() + 1, a.end()), dft(a);
        Z inv = Z(n).inverse();
        for (int i = 0; i < n; i++)a[i] = a[i] * inv;
    }
}


struct Poly : public vector<Z> {
#define T (*this)
    using vector<Z>::vector;
    inline int deg() const {
        return (int)(size());
    }
    inline bool operator <(const Poly &rhs) const{
      return deg() > rhs.deg();
    }
    inline Z operator[](const int &idx) const {
        if (idx < 0 || idx >= deg())return Z(0);
        return at(idx);
    }
    inline Z &operator[](const int &idx) {
        return at(idx);
    }
    inline Poly &operator^=(const Poly &b) {
        if (b.deg() < deg())resize(b.deg());
        for (int i = 0, sz = deg(); i < sz; i++)T[i] *= b[i];
        return T;
    }
    inline Poly &operator<<=(const int &k) {
        return insert(begin(), k, Z(0)), T;
    }
    inline Poly operator<<(const int &r) const {
        return Poly(T) <<= r;
    }
    inline Poly operator>>(const int &r) const {
        return r >= deg() ? Poly() : Poly(begin() + r, end());
    }
    inline Poly &operator>>=(const int &r) {
        return T = T >> r;
    }
    inline Poly mod(const int &k) const {
        return k < deg() ? Poly(begin(), begin() + k) : T;
    }
    inline friend Poly operator*(const Z &a, Poly b) {
        for (auto &x: b)x *= a;
        return b;
    }
    inline friend Poly operator*(Poly b, const Z &a) {
        for (auto &x: b)x *= a;
        return b;
    }
    inline friend Poly operator*(Poly a, Poly b) {
        if (a.empty() || b.empty())return {};
        int sz = 1, tot = a.deg() + b.deg() - 1;
        while (sz < tot)sz <<= 1;
        a.resize(sz), b.resize(sz);
        NTT::dft(a), NTT::dft(b);
        for (int i = 0; i < sz; i++)a[i] *= b[i];
        NTT::idft(a), a.resize(tot);
        return a;
    }
    inline Poly &operator*=(const Poly &b) {
        return T = T * b;
    }
    inline friend Poly operator+(const Poly &a, const Poly &b) {
        int n = (int)max(a.size(), b.size());
        Poly c;
        c.resize(n);
        for (int i = 0, sz = (int)a.size(); i < sz; i++)c[i] = a[i];
        for (int i = 0, sz = (int)b.size(); i < sz; i++)c[i] += b[i];
        return c;
    }
    inline friend Poly operator-(const Poly &a, const Poly &b) {
        int n = (int)max(a.size(), b.size());
        Poly c;
        c.resize(n);
        for (int i = 0, sz = (int)a.size(); i < sz; i++)c[i] = a[i];
        for (int i = 0, sz = (int)b.size(); i < sz; i++)c[i] -= b[i];
        return c;
    }
    inline Poly derivation() const {
        if (T.empty())return {};
        int n = (int)(T.size());
        Poly c;
        c.resize(n - 1);
        for (int i = 0; i < n - 1; i++)c[i] = T[i + 1] * (i + 1);
        return c;
    }
    inline Poly integration() const {
        int n = (int)(T.size());
        Poly c;
        c.resize(n + 1);
        for (int i = 0; i < n; i++)c[i + 1] = T[i] * Z(i + 1).inverse();
        return c;
    }
    inline Poly inv(const int &m) const {
        Poly c{T[0].inverse()};
        int k = 1;
        while (k < m)k <<= 1, c = (c * (Poly{2} - T.mod(k) * c)).mod(k);
        return c.mod(m);
    }
    inline Poly log(const int &m) const {
        return (derivation() * inv(m)).integration().mod(m);
    }
    inline Poly exp(const int &m) const {
        Poly x{1};
        int k = 1;
        while (k < m)k <<= 1, x = (x * (Poly{1} - x.log(k) + mod(k))).mod(k);
        return x.mod(m);
    }
    inline Poly pow(const int &k, const int &m) const {
        int i = 0;
        while (i < T.size() && T[i] == Z(0))i++;
        if (i == T.size() || (LL)i * k >= m)return Poly(m);
        Z v = T[i];
        auto g = (T >> i) * (v.inverse());
        return ((g.log(m - i * k) * Z(k)).exp(m - i * k) << (i * k)) * v.qpow(k);
    }
    inline Poly sqrt(const int &m) const {
        Poly x{1};
        int k = 1;
        while (k < m)k <<= 1, x = (x + (mod(k) * x.inv(k)).mod(k)) * Z(2).inverse();
        return x.mod(m);
    }
    inline Poly rev() const {
        return Poly(rbegin(), rend());
    }
    inline Poly mulT(const Poly &b) const {
        return T * b.rev() >> (b.deg() - 1);
    }
    inline vector<Z> eval(vector<Z> x) const {
        if (T.empty())return vector<Z>(x.size(), Z(0));
        int n = max((int)(x.size()), (int)(T.size()));
        vector<Poly> q(4 * n);
        vector<Z> ans(x.size());
        x.resize(n);
        std::function<void(int, int, int)> build = [&](int rt, int l, int r) {
            if (l == r) {
                q[rt] = {Z(1), -x[l]};
                return;
            }
            int mid = (l + r) >> 1;
            build(rt << 1, l, mid), build(rt << 1 | 1, mid + 1, r);
            q[rt] = q[rt << 1] * q[rt << 1 | 1];
        };
        build(1, 0, n - 1);
        std::function<void(int, int, int, const Poly &)> work = [&](int rt, int l, int r, const Poly &num) {
            if (l == r) {
                if (l < (int)(ans.size()))ans[l] = num[0];
                return;
            }
            int mid = (l + r) >> 1;
            work(rt << 1, l, mid, num.mulT(q[rt << 1 | 1]).mod(mid - l + 1));
            work(rt << 1 | 1, mid + 1, r, num.mulT(q[rt << 1]).mod(r - mid));
        };
        work(1, 0, n - 1, mulT(q[1].inv(n)));
        return ans;
    }
#undef T
};


const int N = 1e6+7;
Z ifac[N], fac[N];

Z binom(int n, int m) {
    if(!m) return 1;
    if(!n || n < m) return 0;
    return fac[n] * ifac[m] * ifac[n - m];
}
Z iep(int x) {
    if(x & 1) return Z(998244352);
    return Z(1);
}

int main() {
    int n, m;
    cin >> n >> m;
    int up = (n * m);
    fac[0] = ifac[0] = Z(1);
    const int M = 1e6;
    for(int i = 1; i <= M; i++) {
        fac[i] = fac[i - 1] * i;
    }
    ifac[M] = fac[M].inverse();
    for(int i = M - 1; i >= 1; i--) {
        ifac[i] = ifac[i + 1] * (i + 1);
    }

    //cout << binom(6, 3).x;

    Poly F;
    for(int i = 0; i <= m; i++) {
        Z res = binom(m, i) * iep(i) * ifac[m - i] * fac[m];
        F.push_back(res);
    }

    //Poly G = F.pow(n,  1000007);
    //Poly G = F.log(1000007);
    //for(int i = 0; i <= up; i++) G[i] *= Z(n);
    //G = G.exp(1000007);

    priority_queue<Poly> Q;
    for(int i = 1; i <= n; i++) Q.push(F);
    while(Q.size() > 1) {
      Poly f1 = Q.top(); Q.pop();
      Poly f2 = Q.top(); Q.pop();
      Poly f3 = f1*f2;
      f3.mod(up+2);
      Q.push(f3);
    }
    Poly G = Q.top();
    Z ans(0);
    for(int i = 0; i <= up; i++) {
        ans += fac[up - i] * G[i];
    }

    cout << ans.x << "\n";
    return 0;
}