#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i, n) for (int i = 0; i < n; i++)
#define all(v) v.begin(), v.end()
template <class T, class U>
inline bool chmax(T &a, U b) {
    if (a < b) {
        a = b;
        return true;
    }
    return false;
}
template <class T, class U>
inline bool chmin(T &a, U b) {
    if (a > b) {
        a = b;
        return true;
    }
    return false;
}
constexpr int INF = 1000000000;
constexpr ll llINF = 3000000000000000000;
constexpr int mod = 998244353;
const ll half = (mod + 1) / 2;
constexpr double eps = 1e-10;
vector<int> prime_list(int n) {
    vector<int> v(n + 1), res;
    for (int i = n; i >= 2; i--) {
        for (int j = i; j <= n; j += i) v[j] = i;
    }
    for (int i = 2; i <= n; i++) {
        if (v[i] == i) res.push_back(i);
    }
    return res;
}
vector<int> next_divisor(int n) {
    vector<int> v(n + 1);
    for (int i = n; i >= 2; i--) {
        for (int j = i; j <= n; j += i) v[j] = i;
    }
    return v;
}
ll modpow(ll a, ll b, ll m = mod) {
    ll res = 1;
    while (b) {
        if (b & 1) {
            res *= a;
            res %= m;
        }
        a *= a;
        a %= m;
        b >>= 1;
    }
    return res;
}
vector<ll> inv, fact, factinv;
void init_fact(int n) {
    inv.resize(n + 1);
    fact.resize(n + 1);
    factinv.resize(n + 1);
    inv[0] = 0;
    inv[1] = 1;
    fact[0] = 1;
    factinv[0] = 1;
    for (ll i = 1; i <= n; i++) {
        if (i >= 2) inv[i] = mod - ((mod / i) * inv[mod % i] % mod);
        fact[i] = (fact[i - 1] * i) % mod;
        factinv[i] = factinv[i - 1] * inv[i] % mod;
    }
}
ll modinv(ll a, ll m = mod) {
    // gcd(a,m) must be 1
    ll b = m, u = 1, v = 0;
    while (b) {
        ll t = a / b;
        a -= t * b;
        swap(a, b);
        u -= t * v;
        swap(u, v);
    }
    u %= m;
    if (u < 0) u += m;
    return u;
}
ll comb(int a, int b) {
    if (a < b || a < 0 || b < 0) return 0;
    return fact[a] * factinv[a - b] % mod * factinv[b] % mod;
}
/*
struct S {
    long long val;
    int sz;
};
using F = long long;

S op(S a, S b) { return S{a.val + b.val, a.sz + b.sz}; }
S e() { return S{0, 0}; }
S mapping(F f, S x) { return S{x.val + f * x.sz, x.sz}; }
F composition(F f, F g) { return f + g; }
F id() { return 0; }
struct segtree {
    int sz = 1;
    vector<S> d;
    vector<F> lz;
    segtree(vector<S> a) {
        int n = a.size();
        while (sz < n) sz <<= 1;
        d.resize(sz * 2 - 1, e());
        lz.resize(sz * 2 - 1, id());
        for (int i = 0; i < n; i++) d[i + sz - 1] = a[i];
        for (int i = sz - 2; i >= 0; i--) d[i] = op(d[i * 2 + 1], d[i * 2 + 2]);
    }
    void eval(int k) {
        d[k] = mapping(lz[k], d[k]);
        if (k <= sz - 2) {
            lz[k * 2 + 1] = composition(lz[k], lz[k * 2 + 1]);
            lz[k * 2 + 2] = composition(lz[k], lz[k * 2 + 2]);
        }
        lz[k] = id();
    }
    void update(int a, int b, F f, int k = 0, int l = 0, int r = -1) {
        eval(k);
        if (r == -1) r = sz;
        if (r <= a || b <= l) return;
        if (a <= l && r <= b) {
            lz[k] = composition(f, lz[k]);
            eval(k);
            return;
        }
        int m = (l + r) >> 1;
        update(a, b, f, k * 2 + 1, l, m);
        update(a, b, f, k * 2 + 2, m, r);
        d[k] = op(d[k * 2 + 1], d[k * 2 + 2]);
    }
    S prod(int a, int b, int k = 0, int l = 0, int r = -1) {
        eval(k);
        if (r == -1) r = sz;
        if (r <= a || b <= l) return e();
        if (a <= l && r <= b) return d[k];
        int m = (l + r) >> 1;
        S vl = prod(a, b, k * 2 + 1, l, m);
        S vr = prod(a, b, k * 2 + 2, m, r);
        return op(vl, vr);
    }
};*/
struct HLD {
    int n;
    vector<int> in, out, sz, par, top, depth;
    vector<vector<int>> g;
    HLD(vector<vector<int>> g) : g(g), n(g.size()), in(n), out(n), sz(n), par(n), top(n), depth(n) {
        dfs_sz(0);
        dfs_hld(0);
    }
    int t = 0;
    void dfs_sz(int v, int p = -1) {
        if (g[v][0] == p && g[v].size() > 1) swap(g[v][0], g[v][1]);
        sz[v] = 1;
        for (int &i : g[v]) {
            if (i == p) continue;
            dfs_sz(i, v);
            sz[v] += sz[i];
            if (sz[g[v][0]] < sz[i]) swap(i, g[v][0]);
        }
    }
    void dfs_hld(int v, int p = -1) {
        in[v] = t++;
        for (int i : g[v]) {
            if (i == p) continue;
            if (i == g[v][0]) {
                // heavy
                par[i] = par[v];
                top[i] = top[v];
                depth[i] = depth[v];
            } else {
                par[i] = v;
                top[i] = i;
                depth[i] = depth[v] + 1;
            }
            dfs_hld(i, v);
        }
        out[v] = t;
    }
};
template <class S, S (*op)(S, S), S (*e)()>
struct segtree {
    int siz = 1;
    vector<S> dat;
    segtree(int n) : segtree(vector<S>(n, e())) {}
    segtree(const vector<S> &a) {
        while (siz < a.size()) siz <<= 1;
        dat = vector<S>(siz << 1, e());
        for (int i = 0; i < a.size(); i++) dat[siz + i] = a[i];
        for (int i = siz - 1; i >= 1; i--) dat[i] = op(dat[2 * i], dat[2 * i + 1]);
    }
    void set(int p, S x) {
        p += siz;
        dat[p] = x;
        while (p > 0) {
            p >>= 1;
            dat[p] = op(dat[2 * p], dat[2 * p + 1]);
        }
    }
    void add(int p, S x) { set(p, get(p) + x); }
    S get(int p) { return dat[p + siz]; }
    S prod(int l, int r) {
        S vl = e(), vr = e();
        l += siz, r += siz;
        while (l < r) {
            if (l & 1) vl = op(vl, dat[l++]);
            if (r & 1) vr = op(dat[--r], vr);
            l >>= 1, r >>= 1;
        }
        return op(vl, vr);
    }
    S all_prod() { return dat[1]; }
};
int op(int a, int b) {
    if (a + b >= mod) return a + b - mod;
    return a + b;
}
int e() { return 0; }
void solve() {
    int n, m;
    cin >> n >> m;
    vector<segtree<int, op, e>> dp(m + 1, segtree<int, op, e>(n + 1));
    segtree<int, op, e> sum(n + 1);
    dp[1].set(0, 1);
    sum.set(0, 1);
    for (int i = 1; i <= n; i++) {
        for (int k = 2; k <= m; k++) {
            // length:[1,k)
            // last:(i-k,i)
            int res = (sum.prod(max(0, i - k + 1), i) + mod - dp[k].prod(max(0, i - k + 1), i)) % mod;
            sum.set(i, op(sum.get(i), res));
            dp[k].set(i, op(dp[k].get(i), res));
        }
    }

    cout << (modpow(m, n) + mod - sum.get(n)) % mod << endl;
}
int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    /*int t;
    cin >> t;
    while (t--)*/
    solve();
}