#include using namespace std; #include using namespace atcoder; using mint = modint998244353; //using mint = modint1000000007; using ll = long long; using ld = long double; using pll = pair; using tlll = tuple; constexpr ll INF = 1LL << 60; template bool chmin(T& a, T b) {if (a > b) {a = b; return true;} return false;} template bool chmax(T& a, T b) {if (a < b) {a = b; return true;} return false;} ll safemod(ll A, ll M) {return (A % M + M) % M;} ll divfloor(ll A, ll B) {if (B < 0) {return divfloor(-A, -B);} return (A - safemod(A, B)) / B;} ll divceil(ll A, ll B) {if (B < 0) {return divceil(-A, -B);} return divfloor(A + B - 1, B);} template void sortunique(vector &V) {sort(V.begin(), V.end()); V.erase(unique(V.begin(), V.end()), V.end());} #define FINALANS(A) do {cout << (A) << '\n'; exit(0);} while (false) class mintcombination { public: vector fac, finv, inv; mintcombination(ll M) { fac.resize(M + 1); finv.resize(M + 1); inv.resize(M + 1); fac.at(0) = 1, finv.at(0) = 1; fac.at(1) = 1, finv.at(1) = 1, inv.at(1) = 1; for (ll i = 2; i <= M; i++) { fac.at(i) = fac.at(i - 1) * i; inv.at(i) = mint::mod() - inv.at(mint::mod() % i) * (mint::mod() / i); finv.at(i) = finv.at(i - 1) * inv.at(i); } } mint P(ll N, ll K) { if (N < K) return 0; if (N < 0 || K < 0) return 0; return fac.at(N) * finv.at(N - K); } mint C(ll N, ll K) { if (N < K) return 0; if (N < 0 || K < 0) return 0; return fac.at(N) * finv.at(K) * finv.at(N - K); } mint H(ll N, ll K) { return C(N + K - 1, K); } }; int main() { ll N, K; cin >> N >> K; //assert(K != 1); if (K == 0) FINALANS(1); if (K == 1) { if ((N - K) % 2 == 0) FINALANS(N - K - 1); else FINALANS(2); } mintcombination com(N + 10); mint ans = 0; for (ll i = 0; i <= N - K; i += 2) { mint tmp = (i + 1) * com.H(K - 1, N - K - i); ans += tmp; //cerr << i << " " << tmp.val() << endl; } cout << ans.val() << endl; }