#include #define rep(i,a,b) for(int i=a;i=b;i--) #define fore(i,a) for(auto &i:a) #define all(x) (x).begin(),(x).end() //#pragma GCC optimize ("-O3") using namespace std; void _main(); int main() { cin.tie(0); ios::sync_with_stdio(false); _main(); } typedef long long ll; const int inf = INT_MAX / 2; const ll infl = 1LL << 60; templatebool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; } templatebool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; } //--------------------------------------------------------------------------------------------------- int mod = 998244353; int add(int x, int y) { return (x += y) >= mod ? x - mod : x; } template int add(int x, T... y) { return add(x, add(y...)); } int mul(int x, int y) { return 1LL * x * y % mod; } template int mul(int x, T... y) { return mul(x, mul(y...)); } int sub(int x, int y) { return add(x, mod - y); } int modpow(int a, long long b) { int ret = 1; while (b > 0) { if (b & 1) ret = 1LL * ret * a % mod; a = 1LL * a * a % mod; b >>= 1; } return ret; } int modinv(int a) { return modpow(a, mod - 2); } typedef vector Vec; typedef vector Mat; Vec mulMatVec(Mat a, Vec b) { int n = b.size(); Vec ret(n, 0); rep(i, 0, n) rep(j, 0, n) ret[i] = add(ret[i], mul(a[i][j], b[j])); return ret; } Mat mulMatMat(Mat a, Mat b) { int n = a.size(); Mat ret(n, Vec(n, 0)); rep(i, 0, n) rep(j, 0, n) rep(k, 0, n) ret[i][j] = add(ret[i][j], mul(a[i][k], b[k][j])); return ret; } Mat fastpow(Mat x, ll n) { Mat ret(x.size(), Vec(x.size(), 0)); rep(i, 0, x.size()) ret[i][i] = 1; while (0 < n) { if ((n % 2) == 0) { x = mulMatMat(x, x); n >>= 1; } else { ret = mulMatMat(ret, x); --n; } } return ret; } void printVec(Vec a) { cout << "[\t"; rep(i, 0, a.size()) cout << a[i] << "\t"; cout << "]" << endl; } void printMat(Mat a) { rep(i, 0, a.size()) printVec(a[i]); } /*---------------------------------------------------------------------------------------------------             ∧_∧       ∧_∧  (´<_` )  Welcome to My Coding Space!      ( ´_ゝ`) /  ⌒i @hamayanhamayan     /   \    | |     /   / ̄ ̄ ̄ ̄/  |   __(__ニつ/  _/ .| .|____      \/____/ (u ⊃ ---------------------------------------------------------------------------------------------------*/ int N, K; //--------------------------------------------------------------------------------------------------- int enc(int ho, int homu, int homura) { return ho * K * K + homu * K + homura; } //--------------------------------------------------------------------------------------------------- void _main() { cin >> N >> K; Mat m(K * K * K, Vec(K * K * K, 0)); Vec v(K * K * K, 0); v[enc(0, 0, 0)] = 1; rep(ho, 0, K) rep(homu, 0, K) rep(homura, 0, K) { // ほ m[enc((ho + 1) % K, homu, homura)][enc(ho, homu, homura)] += 1; // む m[enc(ho, (homu + ho) % K, homura)][enc(ho, homu, homura)] += 1; // ら m[enc(ho, homu, (homura + homu) % K)][enc(ho, homu, homura)] += 1; } m = fastpow(m, N); v = mulMatVec(m, v); int ans = 0; rep(ho, 0, K) rep(homu, 0, K) ans = (ans + v[enc(ho, homu, 0)]) % mod; cout << ans << endl; }