#if 1
// clang-format off
#include <bits/stdc++.h>

#include <atcoder/all>
using namespace atcoder;
using mint93 = modint998244353;
using mint17 = modint1000000007;
using mint = modint;
using vm93 = std::vector<mint93>;
using vvm93 = std::vector<vm93>;
using vm17 = std::vector<mint17>;
using vvm17 = std::vector<vm17>;

using namespace std;
using uint = unsigned int;
using ll = long long;
using ull = unsigned long long;
using lf = long double;
using pll = pair<ll, ll>;
#define vec vector
template <class T> using v = vector<T>;
template <class T> using vv = v<v<T>>;
template <class T> using vvv = v<vv<T>>;
using vl = v<ll>;
using vvl = vv<ll>;
using vvvl = vvv<ll>;
using vpl = v<pll>;
using vs = v<string>;
using vb = v<bool>;
using vvb = v<vb>;
using vvvb = v<vvb>;
template<class T> using PQ = priority_queue<T, v<T>, greater<T>>;
constexpr ll TEN(int n) { return (n == 0) ? 1 : 10 * TEN(n - 1); }

#define FOR(i, a, b) for (ll i = (ll)(a); i < (ll)(b); i++)
#define rep(i, N) for (ll i = 0; i < (ll)(N); i++)
#define rep1(i, N) for (ll i = 1; i <= (ll)(N); i++)
#define rrep(i, N) for (ll i = N - 1; i >= 0; i--)
#define rrep1(i, N) for (ll i = N; i > 0; i--)
#define fore(i, a) for (auto &i : a)
#define fs first
#define sc second
#define eb emplace_back
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define UNIQUE(x) (x).erase(unique((x).begin(), (x).end()), (x).end());
#define YES(x) cout << ((x) ? "YES\n" : "NO\n");
#define Yes(x) cout << ((x) ? "Yes\n" : "No\n");
#define yes(x) cout << ((x) ? "yes\n" : "no\n");
template <class T, class U> void chmin(T &t, const U &u) { if (t > u) t = u; }
template <class T, class U> void chmax(T &t, const U &u) { if (t < u) t = u; }
template <class T> T min(const v<T> &lis) { return *min_element(all(lis)); }
template <class T> T max(v<T> &lis) { return *max_element(all(lis)); }
const int inf = (1 << 30);
const ll infl = (1LL << 60);
const ll mod93 = 998244353;
const ll mod17 = 1000000007;
int popcnt(uint x) { return __builtin_popcount(x); }
int popcnt(ull x) { return __builtin_popcountll(x); }
// 桁数
int bsr(uint x) { return 31 - __builtin_clz(x); }
int bsr(ull x) { return 63 - __builtin_clzll(x); }
// 2で割れる回数
int bsf(uint x) { return __builtin_ctz(x); }
int bsf(ull x) { return __builtin_ctzll(x); }

template <class T, class S> istream &operator>>(istream &is, pair<T, S> &x) { return is >> x.first >> x.second; }
template <class T, class S> ostream &operator<<(ostream &os, const pair<T, S> &x) { return os << x.first << " " << x.second; }
template <class T> istream &operator>>(istream &is, vector<T> &x) { for (auto &y : x) is >> y; return is; }
template <class T> ostream &operator<<(ostream &os, const vector<T> &x) {
  for (size_t i = 0, size = x.size(); i < size; i++)
    os << x[i] << (i == size - 1 ? "" : " ");
  return os;
}

ll rand_int(ll l, ll r) {  // [l, r]
  static random_device rd;
  static mt19937 gen(rd());
  return uniform_int_distribution<ll>(l, r)(gen);
}
template <long long MOD = 998244353> struct binomial {
  long long n;
  std::vector<atcoder::static_modint<MOD>> fact, ifact;
  binomial(long long n) : n(n), fact(n + 1), ifact(n + 1) {
    fact[0] = 1;
    for (int i = 1; i <= n; i++)
      fact[i] = fact[i - 1] * i;
    ifact[n] = fact[n].inv();
    for (int i = n; i > 0; i--)
      ifact[i - 1] = ifact[i] * i;
  }
  atcoder::static_modint<MOD> operator()(int n, int k) {
    if (k < 0 || k > n) return 0;
    return fact[n] * ifact[k] * ifact[n - k];
  }
};

// #include <boost/multiprecision/cpp_int.hpp>
// using cpp_int = boost::multiprecision::cpp_int;

// clang-format on
#endif

// #define _GLIBCXX_DEBUG

struct S {
  array<array<vm93, 3>, 3> A;
};

void add(vm93 &a, vm93 &b) {
  if (a.size() < b.size()) swap(a, b);
  rep(i, b.size()) a[i] += b[i];
}

S e() {
  S ret;
  rep(i, 3) {
    rep(j, 3) {
      ret.A[i][j] = vm93(1);
      if (i == j) ret.A[i][j][0] = 1;
    }
  }
  return ret;
}

S op(S a, S b) {
  S ret;
  rep(now, 3) {
    rep(mid, 3) {
      rep(to, 3) {
        vm93 tmp = convolution(a.A[now][mid], b.A[mid][to]);
        add(ret.A[now][to], tmp);
        while (ret.A[now][to].size() > 0 && ret.A[now][to].back() == 0)
          ret.A[now][to].pop_back();
      }
    }
  }
  return ret;
}

S one() {
  S ret;
  mint93 two = mint93(2).inv();
  mint93 th = mint93(3).inv();
  ret.A = array<array<vm93, 3>, 3>{
      array<vm93, 3>{vm93{0, th}, {0, 2*th},     {}},
      array<vm93, 3>{vm93{0, th}, {0, th}, {th, 0}},
      array<vm93, 3>{    vm93{}, {0, two}, {two, 0}}
  };
  return ret;
}

void print(S a) {
  rep(i, 3) {
    rep(j, 3) {
      cout << "{";
      ll sz = a.A[i][j].size();
      rep(k, sz) {
        if (k > 0) cout << " ";
        cout << a.A[i][j][k].val();
      }
      cout << "}";
    }
    cout << "\n";
  }
}

S doubling(ll N) {
  S ret = e(), cur = one();
  while (N) {
    if (N & 1) ret = op(ret, cur);
    cur = op(cur, cur);
    N >>= 1;
  }
  return ret;
}

struct Solver {
  void solve() {
    ll N, H;
    cin >> N >> H;
    S res = doubling(N - 1);
    // print(res);
    mint93 ans_top = 0, ans_bot = 0;
    rep(i, 3) {
      mint93 tmp_top = 0, tmp_bot = 0;
      rep(j, 3) {
        ll sz = res.A[i][j].size();
        rep(k, sz) { tmp_bot += res.A[i][j][k]; }
        FOR(k, H, sz) { tmp_top += res.A[i][j][k]; }
        if (i != 2 && H - 1 < sz) {
          tmp_top += res.A[i][j][H - 1];
        }
      }
      if (i != 0) tmp_top *= 2, tmp_bot *= 2;
      ans_top += tmp_top;
      ans_bot += tmp_bot;
      // cout << i << " " << tmp_top.val() << " " << tmp_bot.val() << "\n";
    }
    mint93 ans = ans_top / ans_bot;
    // cout << ans_top.val() << " " << ans_bot.val() << "\n";
    cout << ans.val() << "\n";
  }
};

int main() {
  cin.tie(nullptr);
  ios::sync_with_stdio(false);
  cout << fixed << setprecision(20);

  ll t = 1;
  // cin >> t;
  while (t--) {
    Solver solver;
    solver.solve();
  }
}