#include <bits/stdc++.h>
using namespace std;

using ll = long long;
#define rep(i, n) for (ll i = 0; i < (ll)(n); i++)
#define reps(i, n) for (ll i = 1; i <= (ll)(n); i++)
#define all(a) (a).begin(), (a).end()
#define uniq(a) (a).erase(unique(all(a)), (a).end())
#define bit(n) (1LL << (n))
#define dump(a) cerr << #a " = " << (a) << endl
using vll = vector<ll>;
using pll = pair<ll, ll>;
template <typename T> using priority_queue_rev = priority_queue<T, vector<T>, greater<T>>;
constexpr double PI = 3.1415926535897932384626433832795028;
constexpr ll DY[9] = {0, 1, 0, -1, 1, 1, -1, -1, 0};
constexpr ll DX[9] = {1, 0, -1, 0, 1, -1, -1, 1, 0};
ll sign(ll a) { return (a > 0) - (a < 0); }
ll cdiv(ll a, ll b) { return (a - 1 + b) / b; }
template <typename T> T sq(T a) { return a * a; }
template <typename T, typename U> bool chmax(T &a, const U &b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template <typename T, typename U> bool chmin(T &a, const U &b) {
    if (b < a) {
        a = b;
        return true;
    }
    return false;
}
template <typename T, typename U> ostream &operator<<(ostream &os, const pair<T, U> &a) {
    os << "(" << a.first << ", " << a.second << ")";
    return os;
}
template <typename T, typename U, typename V> ostream &operator<<(ostream &os, const tuple<T, U, V> &a) {
    auto [t, u, v] = a;
    os << "(" << t << ", " << u << ", " << v << ")";
    return os;
}
template <typename T> ostream &operator<<(ostream &os, const vector<T> &a) {
    os << "(";
    for (auto itr = a.begin(); itr != a.end(); itr++) { os << *itr << (next(itr) != a.end() ? ", " : ""); }
    os << ")";
    return os;
}
template <typename T> ostream &operator<<(ostream &os, const deque<T> &a) {
    os << "(";
    for (auto itr = a.begin(); itr != a.end(); itr++) { os << *itr << (next(itr) != a.end() ? ", " : ""); }
    os << ")";
    return os;
}
template <typename T> ostream &operator<<(ostream &os, const set<T> &a) {
    os << "{";
    for (auto itr = a.begin(); itr != a.end(); itr++) { os << *itr << (next(itr) != a.end() ? ", " : ""); }
    os << "}";
    return os;
}
template <typename T> ostream &operator<<(ostream &os, const multiset<T> &a) {
    os << "{";
    for (auto itr = a.begin(); itr != a.end(); itr++) { os << *itr << (next(itr) != a.end() ? ", " : ""); }
    os << "}";
    return os;
}
template <typename T, typename U> ostream &operator<<(ostream &os, const map<T, U> &a) {
    os << "{";
    for (auto itr = a.begin(); itr != a.end(); itr++) { os << *itr << (next(itr) != a.end() ? ", " : ""); }
    os << "}";
    return os;
}
struct setup {
    static constexpr ll PREC = 20;
    setup() {
        cout << fixed << setprecision(PREC);
        cerr << fixed << setprecision(PREC);
    };
} setup;

template <ll MOD = 1000000007> struct modint {
    ll val;
    modint(ll val = 0) : val(val >= 0 ? val % MOD : (MOD - (-val) % MOD) % MOD) {}
    modint inv() const {
        ll a = val, b = MOD, u = 1, v = 0, t;
        while (b > 0) {
            t = a / b;
            swap(a -= t * b, b);
            swap(u -= t * v, v);
        }
        return modint(u);
    }
    modint pow(ll p) const {
        modint res = 1, mul = val;
        while (p) {
            if (p & 1) res *= mul;
            mul *= mul;
            p >>= 1;
        }
        return res;
    }
    modint &operator+=(const modint &a) {
        if ((val += a.val) >= MOD) val -= MOD;
        return *this;
    }
    modint &operator-=(const modint &a) {
        if ((val += MOD - a.val) >= MOD) val -= MOD;
        return *this;
    }
    modint &operator*=(const modint &a) {
        (val *= a.val) %= MOD;
        return *this;
    }
    modint &operator/=(const modint &a) { return *this *= a.inv(); }
    bool operator==(const modint &a) const { return val == a.val; }
    bool operator!=(const modint &a) const { return rel_ops::operator!=(*this, a); }
    modint operator+() const { return *this; }
    modint operator-() const { return modint(-val); }
    modint operator+(const modint &a) const { return modint(*this) += a; }
    modint operator-(const modint &a) const { return modint(*this) -= a; }
    modint operator*(const modint &a) const { return modint(*this) *= a; }
    modint operator/(const modint &a) const { return modint(*this) /= a; }
    friend istream &operator>>(istream &is, modint &a) {
        ll val;
        is >> val;
        a = modint(val);
        return is;
    }
    friend ostream &operator<<(ostream &os, const modint &a) { return os << a.val; }
};
using mint = modint<998244353>;

int main() {
    ll n, m;
    cin >> n >> m;
    vector<mint> pn(m + 1);
    rep(i, m + 1) { pn[i] = mint(i).pow(n); }
    auto c = [&](ll d) -> mint {
        if (d < 0) return 0;
        return pn[d + 1];
    };
    auto jc = [&](ll d) -> mint { return c(d) - c(d - 1) * 2 + c(d - 2); };
    auto g = [&](ll d) -> mint {
        if (d < 0) return 0;
        return pn[d + 1] * d / 2;
    };
    auto jg = [&](ll d) -> mint {
        mint ret = 0;
        ret += g(d);
        ret -= g(d - 1);
        ret -= g(d - 1) + c(d - 1);
        ret += g(d - 2) + c(d - 2);
        return ret;
    };
    mint ans = 0;
    rep(d, m) {
        ans += jg(d) * (m - d) * d;
        ans += jc(d) * (m - d) * (m - d + 1) / 2 * d;
    }
    ans *= n;
    cout << ans << endl;
}