#ifdef LOCAL #include "template.hpp" #else #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; namespace io { template istream &operator>>(istream &is, pair &p) { is >> p.first >> p.second; return is; } template istream &operator>>(istream &is, vector &v) { for (auto &x : v) is >> x; return is; } template istream &operator>>(istream &is, array &v) { for (auto &x : v) is >> x; return is; } template istream& cin_tuple_impl(istream &is, T &t) { if constexpr (N < std::tuple_size::value) { auto &x = std::get(t); is >> x; cin_tuple_impl(is, t); } return is; } template istream &operator>>(istream &is, tuple &t) { return cin_tuple_impl(is, t); } template ostream &operator<<(ostream &os, const pair &p) { os << p.first << " " << p.second; return os; } template ostream &operator<<(ostream &os, const vector &v) { int s = (int)v.size(); for (int i = 0; i < s; i++) os << (i ? " " : "") << v[i]; return os; } template ostream &operator<<(ostream &os, const array &v) { size_t n = v.size(); for (size_t i = 0; i < n; i++) { if (i) os << " "; os << v[i]; } return os; } template ostream& cout_tuple_impl(ostream &os, const T &t) { if constexpr (N < std::tuple_size::value) { if constexpr (N > 0) os << " "; const auto &x = std::get(t); os << x; cout_tuple_impl(os, t); } return os; } template ostream &operator<<(ostream &os, const tuple &t) { return cout_tuple_impl(os, t); } void in() {} template void in(T &t, U &...u) { cin >> t; in(u...); } void out() { cout << "\n"; } template void out(const T &t, const U &...u) { cout << t; if (sizeof...(u)) cout << sep; out(u...); } void outr() {} template void outr(const T &t, const U &...u) { cout << t; outr(u...); } void __attribute__((constructor)) _c() { ios_base::sync_with_stdio(false); cin.tie(nullptr); cout << fixed << setprecision(15); } } // namespace io using io::in; using io::out; using io::outr; #define SHOW(x) static_cast(0) using ll = long long; using D = double; using LD = long double; using P = pair; using u8 = uint8_t; using u16 = uint16_t; using u32 = uint32_t; using u64 = uint64_t; using i128 = __int128; using u128 = unsigned __int128; using vi = vector; template using vc = vector; template using vvc = vector>; template using vvvc = vector>; template using vvvvc = vector>; template using vvvvvc = vector>; #define vv(type, name, h, ...) \ vector> name(h, vector(__VA_ARGS__)) #define vvv(type, name, h, w, ...) \ vector>> name( \ h, vector>(w, vector(__VA_ARGS__))) #define vvvv(type, name, a, b, c, ...) \ vector>>> name( \ a, vector>>( \ b, vector>(c, vector(__VA_ARGS__)))) template using PQ = priority_queue>; template using minPQ = priority_queue, greater>; #define rep1(a) for(ll i = 0; i < a; i++) #define rep2(i, a) for(ll i = 0; i < a; i++) #define rep3(i, a, b) for(ll i = a; i < b; i++) #define rep4(i, a, b, c) for(ll i = a; i < b; i += c) #define overload4(a, b, c, d, e, ...) e #define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__) #define rrep1(a) for(ll i = (a)-1; i >= 0; i--) #define rrep2(i, a) for(ll i = (a)-1; i >= 0; i--) #define rrep3(i, a, b) for(ll i = (b)-1; i >= a; i--) #define rrep4(i, a, b, c) for(ll i = (b)-1; i >= a; i -= c) #define rrep(...) overload4(__VA_ARGS__, rrep4, rrep3, rrep2, rrep1)(__VA_ARGS__) #define for_subset(t, s) for (ll t = (s); t >= 0; t = (t == 0 ? -1 : (t - 1) & (s))) #define ALL(v) v.begin(), v.end() #define RALL(v) v.rbegin(), v.rend() #define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() ) #define SZ(v) ll(v.size()) #define MIN(v) *min_element(ALL(v)) #define MAX(v) *max_element(ALL(v)) #define LB(c, x) distance((c).begin(), lower_bound(ALL(c), (x))) #define UB(c, x) distance((c).begin(), upper_bound(ALL(c), (x))) template T SUM(const vector &v) { T res = 0; for(auto &&a : v) res += a; return res; } template vector> RLE(const vector &v) { if (v.empty()) return {}; T cur = v.front(); int cnt = 1; vector> res; for (int i = 1; i < (int)v.size(); i++) { if (cur == v[i]) cnt++; else { res.emplace_back(cur, cnt); cnt = 1; cur = v[i]; } } res.emplace_back(cur, cnt); return res; } template inline bool chmax(T &a, const S &b) { return (a < b ? a = b, true : false); } template inline bool chmin(T &a, const S &b) { return (a > b ? a = b, true : false); } void YESNO(bool flag) { out(flag ? "YES" : "NO"); } void yesno(bool flag) { out(flag ? "Yes" : "No"); } int popcnt(int x) { return __builtin_popcount(x); } int popcnt(u32 x) { return __builtin_popcount(x); } int popcnt(ll x) { return __builtin_popcountll(x); } int popcnt(u64 x) { return __builtin_popcountll(x); } int popcnt_sgn(int x) { return (__builtin_parity(x) & 1 ? -1 : 1); } int popcnt_sgn(u32 x) { return (__builtin_parity(x) & 1 ? -1 : 1); } int popcnt_sgn(ll x) { return (__builtin_parityl(x) & 1 ? -1 : 1); } int popcnt_sgn(u64 x) { return (__builtin_parityl(x) & 1 ? -1 : 1); } int highbit(int x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); } int highbit(u32 x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); } int highbit(ll x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); } int highbit(u64 x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); } int lowbit(int x) { return (x == 0 ? -1 : __builtin_ctz(x)); } int lowbit(u32 x) { return (x == 0 ? -1 : __builtin_ctz(x)); } int lowbit(ll x) { return (x == 0 ? -1 : __builtin_ctzll(x)); } int lowbit(u64 x) { return (x == 0 ? -1 : __builtin_ctzll(x)); } template T get_bit(T x, int k) { return x >> k & 1; } template T set_bit(T x, int k) { return x | T(1) << k; } template T reset_bit(T x, int k) { return x & ~(T(1) << k); } template T flip_bit(T x, int k) { return x ^ T(1) << k; } template T popf(deque &que) { T a = que.front(); que.pop_front(); return a; } template T popb(deque &que) { T a = que.back(); que.pop_back(); return a; } template T pop(queue &que) { T a = que.front(); que.pop(); return a; } template T pop(stack &que) { T a = que.top(); que.pop(); return a; } template T pop(PQ &que) { T a = que.top(); que.pop(); return a; } template T pop(minPQ &que) { T a = que.top(); que.pop(); return a; } template ll binary_search(F check, ll ok, ll ng, bool check_ok = true) { if (check_ok) assert(check(ok)); while (abs(ok - ng) > 1) { ll mid = (ok + ng) / 2; (check(mid) ? ok : ng) = mid; } return ok; } template double binary_search_real(F check, double ok, double ng, int iter = 60) { for (int _ = 0; _ < iter; _++) { double mid = (ok + ng) / 2; (check(mid) ? ok : ng) = mid; } return (ok + ng) / 2; } // max x s.t. b*x <= a ll div_floor(ll a, ll b) { assert(b != 0); if (b < 0) a = -a, b = -b; return a / b - (a % b < 0); } // max x s.t. b*x < a ll div_under(ll a, ll b) { assert(b != 0); if (b < 0) a = -a, b = -b; return a / b - (a % b <= 0); } // min x s.t. b*x >= a ll div_ceil(ll a, ll b) { assert(b != 0); if (b < 0) a = -a, b = -b; return a / b + (a % b > 0); } // min x s.t. b*x > a ll div_over(ll a, ll b) { assert(b != 0); if (b < 0) a = -a, b = -b; return a / b + (a % b >= 0); } // x = a mod b (b > 0), 0 <= x < b ll modulo(ll a, ll b) { assert(b > 0); ll c = a % b; return c < 0 ? c + b : c; } // (q,r) s.t. a = b*q + r, 0 <= r < b (b > 0) // div_floor(a,b), modulo(a,b) pair divmod(ll a, ll b) { ll q = div_floor(a,b); return {q, a - b*q}; } #endif template struct LazyMontgomeryModInt { using mint = LazyMontgomeryModInt; using i32 = int32_t; using u32 = uint32_t; using u64 = uint64_t; static constexpr u32 get_r() { u32 ret = mod; for (i32 i = 0; i < 4; ++i) ret *= 2 - mod * ret; return ret; } static constexpr u32 r = get_r(); static constexpr u32 n2 = -u64(mod) % mod; static_assert(mod < (1 << 30), "invalid, mod >= 2 ^ 30"); static_assert((mod & 1) == 1, "invalid, mod % 2 == 0"); static_assert(r * mod == 1, "this code has bugs."); u32 a; constexpr LazyMontgomeryModInt() : a(0) {} constexpr LazyMontgomeryModInt(const int64_t &b) : a(reduce(u64(b % mod + mod) * n2)){}; static constexpr u32 reduce(const u64 &b) { return (b + u64(u32(b) * u32(-r)) * mod) >> 32; } constexpr mint &operator+=(const mint &b) { if (i32(a += b.a - 2 * mod) < 0) a += 2 * mod; return *this; } constexpr mint &operator-=(const mint &b) { if (i32(a -= b.a) < 0) a += 2 * mod; return *this; } constexpr mint &operator*=(const mint &b) { a = reduce(u64(a) * b.a); return *this; } constexpr mint &operator/=(const mint &b) { *this *= b.inverse(); return *this; } constexpr mint operator+(const mint &b) const { return mint(*this) += b; } constexpr mint operator-(const mint &b) const { return mint(*this) -= b; } constexpr mint operator*(const mint &b) const { return mint(*this) *= b; } constexpr mint operator/(const mint &b) const { return mint(*this) /= b; } constexpr bool operator==(const mint &b) const { return (a >= mod ? a - mod : a) == (b.a >= mod ? b.a - mod : b.a); } constexpr bool operator!=(const mint &b) const { return (a >= mod ? a - mod : a) != (b.a >= mod ? b.a - mod : b.a); } constexpr mint operator-() const { return mint() - mint(*this); } constexpr mint operator+() const { return mint(*this); } constexpr mint pow(u64 n) const { mint ret(1), mul(*this); while (n > 0) { if (n & 1) ret *= mul; mul *= mul; n >>= 1; } return ret; } constexpr mint inverse() const { int x = get(), y = mod, u = 1, v = 0, t = 0, tmp = 0; while (y > 0) { t = x / y; x -= t * y, u -= t * v; tmp = x, x = y, y = tmp; tmp = u, u = v, v = tmp; } return mint{u}; } friend ostream &operator<<(ostream &os, const mint &b) { return os << b.get(); } friend istream &operator>>(istream &is, mint &b) { int64_t t; is >> t; b = LazyMontgomeryModInt(t); return (is); } constexpr u32 get() const { u32 ret = reduce(a); return ret >= mod ? ret - mod : ret; } static constexpr u32 get_mod() { return mod; } }; const int mod = 998244353; //const int mod = 1000000007; using mint = LazyMontgomeryModInt; const int B = 1000000; const vc f = {1,373341033,45596018,834980587,623627864,428937595,442819817,499710224,833655840,83857087,295201906,788488293,671639287,849315549,597398273,813259672,732727656,244038325,122642896,310517972,160030060,483239722,683879839,712910418,384710263,433880730,844360005,513089677,101492974,959253371,957629942,678615452,34035221,56734233,524027922,31729117,102311167,330331487,8332991,832392662,545208507,594075875,318497156,859275605,300738984,767818091,864118508,878131539,316588744,812496962,213689172,584871249,980836133,54096741,417876813,363266670,335481797,730839588,393495668,435793297,760025067,811438469,720976283,650770098,586537547,117371703,566486504,749562308,708205284,932912293,939830261,983699513,206579820,301188781,593164676,770845925,247687458,41047791,266419267,937835947,506268060,6177705,936268003,166873118,443834893,328979964,470135404,954410105,117565665,832761782,39806322,478922755,394880724,821825588,468705875,512554988,232240472,876497899,356048018,895187265,808258749,575505950,68190615,939065335,552199946,694814243,385460530,529769387,640377761,916128300,440133909,362216114,826373774,502324157,457648395,385510728,904737188,78988746,454565719,623828097,686156489,713476044,63602402,570334625,681055904,222059821,477211096,343363294,833792655,461853093,741797144,74731896,930484262,268372735,941222802,677432735,474842829,700451655,400176109,697644778,390377694,790010794,360642718,505712943,946647976,339045014,715797300,251680896,70091750,40517433,12629586,850635539,110877109,571935891,695965747,634938288,69072133,155093216,749696762,963086402,544711799,724471925,334646013,574791029,722417626,377929821,743946412,988034679,405207112,18063742,104121967,638607426,607304611,751377777,35834555,313632531,18058363,656121134,40763559,562910912,495867250,48767038,210864657,659137294,715390025,865854329,324322857,388911184,286059202,636456178,421290700,832276048,726437551,526417714,252522639,386147469,674313019,274769381,226519400,272047186,117153405,712896591,486826649,119444874,338909703,18536028,41814114,245606459,140617938,250512392,57084755,157807456,261113192,40258068,194807105,325341339,884328111,896332013,880836012,737358206,202713771,785454372,399586250,485457499,640827004,546969497,749602473,159788463,159111724,218592929,675932866,314795475,811539323,246883213,696818315,759880589,4302336,353070689,477909706,559289160,79781699,878094972,840903973,367416824,973366814,848259019,462421750,667227759,897917455,81800722,956276337,942686845,420541799,417005912,272641764,941778993,217214373,192220616,267901132,50530621,652678397,354880856,164289049,781023184,105376215,315094878,607856504,733905911,457743498,992735713,35212756,231822660,276036750,734558079,424180850,433186147,308380947,18333316,12935086,351491725,655645460,535812389,521902115,67016984,48682076,64748124,489360447,361275315,786336279,805161272,468129309,645091350,887284732,913004502,358814684,281295633,328970139,395955130,164840186,820902807,761699708,246274415,592331769,913846362,866682684,600130702,903837674,529462989,90612675,526540127,533047427,110008879,674279751,801920753,645226926,676886948,752481486,474034007,457790341,166813684,287671032,188118664,244731384,404032157,269766986,423996017,182948540,356801634,737863144,652014069,206068022,504569410,919894484,593398649,963768176,882517476,702523597,949028249,128957299,171997372,50865043,20937461,690959202,581356488,369182214,993580422,193500140,540665426,365786018,743731625,144980423,979536721,773259009,617053935,247670131,843705280,30419459,985463402,261585206,237885042,111276893,488166208,137660292,720784236,244467770,26368504,792857103,666885724,670313309,905683034,259415897,512017253,826265493,111960112,633652060,918048438,516432938,386972415,996212724,610073831,444094191,72480267,665038087,11584804,301029012,723617861,113763819,778259899,937766095,535448641,593907889,783573565,673298635,599533244,655712590,173350007,868198597,169013813,585161712,697502214,573994984,285943986,675831407,3134056,965907646,401920943,665949756,236277883,612745912,813282113,892454686,901222267,624900982,927122298,686321335,84924870,927606072,506664166,353631992,165913238,566073550,816674343,864877926,171259407,908752311,874007723,803597299,613676466,880336545,282280109,128761001,58852065,474075900,434816091,364856903,149123648,388854780,314693916,423183826,419733481,888483202,238933227,336564048,757103493,100189123,855479832,51370348,403061033,496971759,831753030,251718753,272779384,683379259,488844621,881783783,659478190,445719559,740782647,546525906,985524427,548033568,333772553,331916427,752533273,730387628,93829695,655989476,930661318,334885743,466041862,428105027,888238707,232218076,769865249,730641039,616996159,231721356,326973501,426068899,722403656,742756734,663270261,364187931,350431704,671823672,633125919,226166717,386814657,237594135,451479365,546182474,119366536,465211069,605313606,728508871,249619035,663053607,900453742,48293872,229958401,62402409,69570431,71921532,960467929,537087913,514588945,5138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mint fact(int n) { mint ret = f[n/B]; rep(i,(n/B)*B+1, n+1) ret *= i; return ret; } void solve() { int n,k; in(n,k); if(n >= mod){ if(k >= mod or n-k >= mod){ mint ans = 1; rep(i,min(k, n-k)) ans *= n-i, ans /= (i+1); out(ans); } else out(0); } else{ out(fact(n) * fact(k).inverse() * fact(n-k).inverse()); } } int main() { int tc = 1; // in(tc); while(tc--){ solve(); } }