#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define all(a) (a).begin(), (a).end() #define rep(i, n) for (ll i = 0; i < (n); i++) #define req(i, a, b) for (ll i = (a); i < (b); i++) #define pb push_back #define debug(x) cerr << __LINE__ << ' ' << #x << ':' << (x) << '\n' #define debug2(x, y) cerr << __LINE__ << ' ' << #x << ':' << (x) << ',' << #y << ':' << (y) << '\n' #define debug3(x, y, z) cerr << __LINE__ << ' ' << #x << ':' << (x) << ',' << #y << ':' << (y) << ',' << #z << ':' << (z) << '\n' #pragma GCC optimize("O3") #pragma GCC optimize("unroll-loops") using namespace std; typedef long long ll; typedef unsigned int uint; typedef unsigned long long ull; typedef long double ld; template using P = pair; template using pri_s = priority_queue, greater>; template using pri_b = priority_queue; constexpr int inf = 1000000010; constexpr int inf2 = 2000000010; constexpr ll INF = 1000000000000000010; constexpr ll INF4 = 4000000000000000010; constexpr int mod1e9 = 1000000007; constexpr int mod998 = 998244353; constexpr ld eps = 1e-12; constexpr ld pi = 3.141592653589793238; constexpr ll ten(int n) { return n ? 10 * ten(n - 1) : 1; }; int dx[] = { 1,0,-1,0,1,1,-1,-1,0 }; int dy[] = { 0,1,0,-1,1,-1,1,-1,0 }; ll mul(ll a, ll b) { return (b != 0 && a > INF / b ? INF : a * b); } void fail() { cout << "-1\n"; exit(0); } void no() { cout << "No\n"; exit(0); } template void er(T a) { cout << a << '\n'; exit(0); } template inline bool chmax(T &a, const U &b) { if (a < b) { a = b; return true; } return false; } template inline bool chmin(T &a, const U &b) { if (a > b) { a = b; return true; } return false; } template istream &operator >>(istream &s, vector &v) { for (auto &e : v) s >> e; return s; } template ostream &operator <<(ostream &s, const vector &v) { for (auto &e : v) s << e << ' '; return s; } template ostream &operator << (ostream &s, const pair &p) { s << p.first << ' ' << p.second; return s; } struct fastio { fastio() { cin.tie(0); cout.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); cerr << fixed << setprecision(20); } }fastio_; #include using namespace atcoder; constexpr ll mod = mod998; using mint = static_modint; istream &operator >>(istream &s, mint &m) { ll y; s >> y; m = y; return s; } ostream &operator <<(ostream &s, mint &m) { return s << m.val(); } ostream &operator <<(ostream &s, const vector &v) { for (auto &e : v) s << e.val() << ' '; return s; } vector fac, inv, facinv; void modcalc(int n) { fac.resize(n); inv.resize(n); facinv.resize(n); fac[0] = 1; fac[1] = 1; inv[1] = 1; facinv[0] = 1; facinv[1] = 1; for (ll i = 2; i < n; i++) { fac[i] = fac[i - 1] * i; inv[i] = -inv[mod % i] * (mod / i); facinv[i] = facinv[i - 1] * inv[i]; } } mint comb(ll n, ll k) { if (n < 0 || k < 0 || n < k) return 0; return fac[n] * facinv[k] * facinv[n - k]; } mint perm(ll n, ll k) { if (n < 0 || k < 0 || n < k) return 0; return fac[n] * facinv[n - k]; } mint hom(ll n, ll k) { if (n < 0 || k < 0 || n == 0 && k > 0) return 0; if (n == 0 && k == 0) return 1; return fac[n + k - 1] * facinv[k] * facinv[n - 1]; } int main() { modcalc(300000); ll n, k; cin >> n >> k; mint a = 0, b = 0, c = 0; if(k % 4 == 0 or (n % 2 == 1 && k % 2 == 0)) c = comb(n / 2 + 1, k / 4); if(n % 2 == 1) b += comb((n / 2 + 1) * 2, k / 2) - c; if(n % 2 == 1 && k % 2 == 0) b += comb((n / 2 + 1) * 2, k / 2 - 1) - c; b *= 2; if(k % 2 == 0) b += comb(n + 2, k / 2) - c; a = comb(2 * n + 4, k); a -= b + c; mint ans = a * inv[4] + b * inv[2] + c; cout << ans << '\n'; }