結果
| 問題 | No.3394 Big Binom |
| コンテスト | |
| ユーザー |
 emthrm
|
| 提出日時 | 2025-12-01 22:33:31 |
| 言語 | C++23 (gcc 13.3.0 + boost 1.89.0) |
| 結果 |
AC
|
| 実行時間 | 276 ms / 2,000 ms |
| コード長 | 20,959 bytes |
| 記録 | |
| コンパイル時間 | 4,663 ms |
| コンパイル使用メモリ | 323,904 KB |
| 実行使用メモリ | 11,616 KB |
| 最終ジャッジ日時 | 2025-12-14 20:01:31 |
| 合計ジャッジ時間 | 8,200 ms |
|
ジャッジサーバーID （参考情報） |
judge4 / judge2 |
（要ログイン）
| ファイルパターン | 結果 |
|---|---|
| sample | AC * 4 |
| other | AC * 22 |
ソースコード
// https://github.com/yosupo06/library-checker-problems/blob/4fcedb6dcaf1b768b2de93324d6bfa395a5b05e6/enumerative_combinatorics/factorial/sol/correct.cpp
#include <cstdio>
#include <vector>
#include <cassert>
#include <array>
using namespace std;
using ll = long long;
using u32 = unsigned int;
using u64 = unsigned long long;
using u128 = unsigned __int128;
using pi = pair<ll, ll>;
using vi = vector<ll>;
template <class T>
using vc = vector<T>;
template <class T>
using vvc = vector<vc<T>>;
template <class T>
using vvvc = vector<vvc<T>>;
#define vv(type, name, h, ...) \
vector<vector<type>> name(h, vector<type>(__VA_ARGS__))
#define vvv(type, name, h, w, ...) \
vector<vector<vector<type>>> name( \
h, vector<vector<type>>(w, vector<type>(__VA_ARGS__)))
#define FOR1(a) for (ll _ = 0; _ < ll(a); ++_)
#define FOR2(i, a) for (ll i = 0; i < ll(a); ++i)
#define FOR3(i, a, b) for (ll i = a; i < ll(b); ++i)
#define FOR4(i, a, b, c) for (ll i = a; i < ll(b); i += (c))
#define FOR1_R(a) for (ll i = (a)-1; i >= ll(0); --i)
#define FOR2_R(i, a) for (ll i = (a)-1; i >= ll(0); --i)
#define FOR3_R(i, a, b) for (ll i = (b)-1; i >= ll(a); --i)
#define overload4(a, b, c, d, e, ...) e
#define overload3(a, b, c, d, ...) d
#define FOR(...) overload4(__VA_ARGS__, FOR4, FOR3, FOR2, FOR1)(__VA_ARGS__)
#define FOR_R(...) overload3(__VA_ARGS__, FOR3_R, FOR2_R, FOR1_R)(__VA_ARGS__)
#define len(x) ll(x.size())
#define elif else if
#define eb emplace_back
#define mp make_pair
#define mt make_tuple
#define fi first
#define se second
// (0, 1, 2, 3, 4) -> (-1, 0, 1, 1, 2)
int topbit(int x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); }
int topbit(u32 x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); }
int topbit(ll x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); }
int topbit(u64 x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); }
template <typename mint>
mint inv(int n) {
static const int mod = mint::get_mod();
static vector<mint> dat = {0, 1};
assert(0 <= n);
if (n >= mod) n %= mod;
while (len(dat) <= n) {
int k = len(dat);
int q = (mod + k - 1) / k;
dat.eb(dat[k * q - mod] * mint::raw(q));
}
return dat[n];
}
template <typename mint>
mint fact(int n) {
static const int mod = mint::get_mod();
assert(0 <= n && n < mod);
static vector<mint> dat = {1, 1};
while (len(dat) <= n) dat.eb(dat[len(dat) - 1] * mint::raw(len(dat)));
return dat[n];
}
template <typename mint>
mint fact_inv(int n) {
static vector<mint> dat = {1, 1};
if (n < 0) return mint(0);
while (len(dat) <= n) dat.eb(dat[len(dat) - 1] * inv<mint>(len(dat)));
return dat[n];
}
template <class mint, class... Ts>
mint fact_invs(Ts... xs) {
return (mint(1) * ... * fact_inv<mint>(xs));
}
template <int mod>
struct modint {
static constexpr u32 umod = u32(mod);
static_assert(umod < u32(1) << 31);
u32 val;
static modint raw(u32 v) {
modint x;
x.val = v;
return x;
}
constexpr modint() : val(0) {}
constexpr modint(u32 x) : val(x % umod) {}
constexpr modint(u64 x) : val(x % umod) {}
constexpr modint(int x) : val((x %= mod) < 0 ? x + mod : x){};
constexpr modint(ll x) : val((x %= mod) < 0 ? x + mod : x){};
bool operator<(const modint &other) const { return val < other.val; }
modint &operator+=(const modint &p) {
if ((val += p.val) >= umod) val -= umod;
return *this;
}
modint &operator-=(const modint &p) {
if ((val += umod - p.val) >= umod) val -= umod;
return *this;
}
modint &operator*=(const modint &p) {
val = u64(val) * p.val % umod;
return *this;
}
modint &operator/=(const modint &p) {
*this *= p.inverse();
return *this;
}
modint operator-() const { return modint::raw(val ? mod - val : u32(0)); }
modint operator+(const modint &p) const { return modint(*this) += p; }
modint operator-(const modint &p) const { return modint(*this) -= p; }
modint operator*(const modint &p) const { return modint(*this) *= p; }
modint operator/(const modint &p) const { return modint(*this) /= p; }
bool operator==(const modint &p) const { return val == p.val; }
bool operator!=(const modint &p) const { return val != p.val; }
modint inverse() const {
int a = val, b = mod, u = 1, v = 0, t;
while (b > 0) {
t = a / b;
swap(a -= t * b, b), swap(u -= t * v, v);
}
return modint(u);
}
modint pow(ll n) const {
assert(n >= 0);
modint ret(1), mul(val);
while (n > 0) {
if (n & 1) ret *= mul;
mul *= mul;
n >>= 1;
}
return ret;
}
static constexpr int get_mod() { return mod; }
// (n, r), r は 1 の 2^n 乗根
static constexpr pair<int, int> ntt_info() {
if (mod == 167772161) return {25, 17};
if (mod == 469762049) return {26, 30};
if (mod == 754974721) return {24, 362};
if (mod == 880803841) return {23, 211};
if (mod == 943718401) return {22, 663003469};
if (mod == 998244353) return {23, 31};
if (mod == 1045430273) return {20, 363};
if (mod == 1051721729) return {20, 330};
if (mod == 1053818881) return {20, 2789};
return {-1, -1};
}
static constexpr bool can_ntt() { return ntt_info().fi != -1; }
};
using modint998 = modint<998244353>;
template <class T>
vc<vc<T>> matrix_mul(const vc<vc<T>> &A, const vc<vc<T>> &B, int N1 = -1,
int N2 = -1, int N3 = -1) {
if (N1 == -1) { N1 = len(A), N2 = len(B), N3 = len(B[0]); }
vv(u32, b, N3, N2);
FOR(i, N2) FOR(j, N3) b[j][i] = B[i][j].val;
vv(T, C, N1, N3);
if ((T::get_mod() < (1 << 30)) && N2 <= 16) {
FOR(i, N1) FOR(j, N3) {
u64 sm = 0;
FOR(m, N2) sm += u64(A[i][m].val) * b[j][m];
C[i][j] = sm;
}
} else {
FOR(i, N1) FOR(j, N3) {
u128 sm = 0;
FOR(m, N2) sm += u64(A[i][m].val) * b[j][m];
C[i][j] = T::raw(sm % (T::get_mod()));
}
}
return C;
}
template <class T>
struct Monoid_Mul {
using value_type = T;
using X = T;
static constexpr X op(const X &x, const X &y) noexcept { return x * y; }
static constexpr X inverse(const X &x) noexcept { return X(1) / x; }
static constexpr X unit() { return X(1); }
static constexpr bool commute = true;
};
template <class Monoid>
struct Sliding_Window_Aggregation {
using X = typename Monoid::value_type;
using value_type = X;
int sz = 0;
vc<X> dat;
vc<X> cum_l;
X cum_r;
Sliding_Window_Aggregation()
: cum_l({Monoid::unit()}), cum_r(Monoid::unit()) {}
int size() { return sz; }
void push(X x) {
++sz;
cum_r = Monoid::op(cum_r, x);
dat.eb(x);
}
void pop() {
--sz;
cum_l.pop_back();
if (len(cum_l) == 0) {
cum_l = {Monoid::unit()};
cum_r = Monoid::unit();
while (len(dat) > 1) {
cum_l.eb(Monoid::op(dat.back(), cum_l.back()));
dat.pop_back();
}
dat.pop_back();
}
}
X lprod() { return cum_l.back(); }
X rprod() { return cum_r; }
X prod() { return Monoid::op(cum_l.back(), cum_r); }
};
// long でも大丈夫
// (val * x - 1) が mod の倍数になるようにする
// 特に mod=0 なら x=0 が満たす
ll mod_inv(ll val, ll mod) {
assert(mod >= 0);
if (mod == 0) return 0;
val %= mod;
if (val < 0) val += mod;
ll a = val, b = mod, u = 1, v = 0, t;
while (b > 0) {
t = a / b;
swap(a -= t * b, b), swap(u -= t * v, v);
}
if (u < 0) u += mod;
return u;
}
constexpr u32 mod_pow_constexpr(u64 a, u64 n, u32 mod) {
a %= mod;
u64 res = 1;
FOR(32) {
if (n & 1) res = res * a % mod;
a = a * a % mod, n /= 2;
}
return res;
}
template <typename T, u32 p0, u32 p1, u32 p2>
T CRT3(u64 a0, u64 a1, u64 a2) {
static_assert(p0 < p1 && p1 < p2);
static constexpr u64 x0_1 = mod_pow_constexpr(p0, p1 - 2, p1);
static constexpr u64 x01_2 = mod_pow_constexpr(u64(p0) * p1 % p2, p2 - 2, p2);
u64 c = (a1 - a0 + p1) * x0_1 % p1;
u64 a = a0 + c * p0;
c = (a2 - a % p2 + p2) * x01_2 % p2;
return T(a) + T(c) * T(p0) * T(p1);
}
template <class T>
vc<T> convolution_naive(const vc<T> &a, const vc<T> &b) {
int n = int(a.size()), m = int(b.size());
if (n > m) return convolution_naive<T>(b, a);
if (n == 0) return {};
vc<T> ans(n + m - 1);
if (n <= 16 && (T::get_mod() < (1 << 30))) {
for (int k = 0; k < n + m - 1; ++k) {
int s = max(0, k - m + 1);
int t = min(n, k + 1);
u64 sm = 0;
for (int i = s; i < t; ++i) { sm += u64(a[i].val) * (b[k - i].val); }
ans[k] = sm;
}
} else {
for (int k = 0; k < n + m - 1; ++k) {
int s = max(0, k - m + 1);
int t = min(n, k + 1);
u128 sm = 0;
for (int i = s; i < t; ++i) { sm += u64(a[i].val) * (b[k - i].val); }
ans[k] = T::raw(sm % T::get_mod());
}
}
return ans;
}
template <typename T>
vc<T> convolution_karatsuba(const vc<T> &f, const vc<T> &g) {
const int thresh = 30;
if (min(len(f), len(g)) <= thresh) return convolution_naive(f, g);
int n = max(len(f), len(g));
int m = (n + 1) / 2;
vc<T> f1, f2, g1, g2;
if (len(f) < m) f1 = f;
if (len(f) >= m) f1 = {f.begin(), f.begin() + m};
if (len(f) >= m) f2 = {f.begin() + m, f.end()};
if (len(g) < m) g1 = g;
if (len(g) >= m) g1 = {g.begin(), g.begin() + m};
if (len(g) >= m) g2 = {g.begin() + m, g.end()};
vc<T> a = convolution_karatsuba(f1, g1);
vc<T> b = convolution_karatsuba(f2, g2);
FOR(i, len(f2)) f1[i] += f2[i];
FOR(i, len(g2)) g1[i] += g2[i];
vc<T> c = convolution_karatsuba(f1, g1);
vc<T> F(len(f) + len(g) - 1);
assert(2 * m + len(b) <= len(F));
FOR(i, len(a)) F[i] += a[i], c[i] -= a[i];
FOR(i, len(b)) F[2 * m + i] += b[i], c[i] -= b[i];
if (c.back() == T(0)) c.pop_back();
FOR(i, len(c)) if (c[i] != T(0)) F[m + i] += c[i];
return F;
}
template <class mint>
void ntt(vector<mint> &a, bool inverse) {
assert(mint::can_ntt());
const int rank2 = mint::ntt_info().fi;
const int mod = mint::get_mod();
static array<mint, 30> root, iroot;
static array<mint, 30> rate2, irate2;
static array<mint, 30> rate3, irate3;
static bool prepared = 0;
if (!prepared) {
prepared = 1;
root[rank2] = mint::ntt_info().se;
iroot[rank2] = mint(1) / root[rank2];
FOR_R(i, rank2) {
root[i] = root[i + 1] * root[i + 1];
iroot[i] = iroot[i + 1] * iroot[i + 1];
}
mint prod = 1, iprod = 1;
for (int i = 0; i <= rank2 - 2; i++) {
rate2[i] = root[i + 2] * prod;
irate2[i] = iroot[i + 2] * iprod;
prod *= iroot[i + 2];
iprod *= root[i + 2];
}
prod = 1, iprod = 1;
for (int i = 0; i <= rank2 - 3; i++) {
rate3[i] = root[i + 3] * prod;
irate3[i] = iroot[i + 3] * iprod;
prod *= iroot[i + 3];
iprod *= root[i + 3];
}
}
int n = int(a.size());
int h = topbit(n);
assert(n == 1 << h);
if (!inverse) {
int len = 0;
while (len < h) {
if (h - len == 1) {
int p = 1 << (h - len - 1);
mint rot = 1;
FOR(s, 1 << len) {
int offset = s << (h - len);
FOR(i, p) {
auto l = a[i + offset];
auto r = a[i + offset + p] * rot;
a[i + offset] = l + r;
a[i + offset + p] = l - r;
}
rot *= rate2[topbit(~s & -~s)];
}
len++;
} else {
int p = 1 << (h - len - 2);
mint rot = 1, imag = root[2];
for (int s = 0; s < (1 << len); s++) {
mint rot2 = rot * rot;
mint rot3 = rot2 * rot;
int offset = s << (h - len);
for (int i = 0; i < p; i++) {
u64 mod2 = u64(mod) * mod;
u64 a0 = a[i + offset].val;
u64 a1 = u64(a[i + offset + p].val) * rot.val;
u64 a2 = u64(a[i + offset + 2 * p].val) * rot2.val;
u64 a3 = u64(a[i + offset + 3 * p].val) * rot3.val;
u64 a1na3imag = (a1 + mod2 - a3) % mod * imag.val;
u64 na2 = mod2 - a2;
a[i + offset] = a0 + a2 + a1 + a3;
a[i + offset + 1 * p] = a0 + a2 + (2 * mod2 - (a1 + a3));
a[i + offset + 2 * p] = a0 + na2 + a1na3imag;
a[i + offset + 3 * p] = a0 + na2 + (mod2 - a1na3imag);
}
rot *= rate3[topbit(~s & -~s)];
}
len += 2;
}
}
} else {
mint coef = mint(1) / mint(len(a));
FOR(i, len(a)) a[i] *= coef;
int len = h;
while (len) {
if (len == 1) {
int p = 1 << (h - len);
mint irot = 1;
FOR(s, 1 << (len - 1)) {
int offset = s << (h - len + 1);
FOR(i, p) {
u64 l = a[i + offset].val;
u64 r = a[i + offset + p].val;
a[i + offset] = l + r;
a[i + offset + p] = (mod + l - r) * irot.val;
}
irot *= irate2[topbit(~s & -~s)];
}
len--;
} else {
int p = 1 << (h - len);
mint irot = 1, iimag = iroot[2];
FOR(s, (1 << (len - 2))) {
mint irot2 = irot * irot;
mint irot3 = irot2 * irot;
int offset = s << (h - len + 2);
for (int i = 0; i < p; i++) {
u64 a0 = a[i + offset + 0 * p].val;
u64 a1 = a[i + offset + 1 * p].val;
u64 a2 = a[i + offset + 2 * p].val;
u64 a3 = a[i + offset + 3 * p].val;
u64 x = (mod + a2 - a3) * iimag.val % mod;
a[i + offset] = a0 + a1 + a2 + a3;
a[i + offset + 1 * p] = (a0 + mod - a1 + x) * irot.val;
a[i + offset + 2 * p] = (a0 + a1 + 2 * mod - a2 - a3) * irot2.val;
a[i + offset + 3 * p] = (a0 + 2 * mod - a1 - x) * irot3.val;
}
irot *= irate3[topbit(~s & -~s)];
}
len -= 2;
}
}
}
}
template <class mint>
vector<mint> convolution_ntt(vector<mint> a, vector<mint> b) {
if (a.empty() || b.empty()) return {};
int n = int(a.size()), m = int(b.size());
int sz = 1;
while (sz < n + m - 1) sz *= 2;
// sz = 2^k のときの高速化。分割統治的なやつで損しまくるので。
if ((n + m - 3) <= sz / 2) {
auto a_last = a.back(), b_last = b.back();
a.pop_back(), b.pop_back();
auto c = convolution(a, b);
c.resize(n + m - 1);
c[n + m - 2] = a_last * b_last;
FOR(i, len(a)) c[i + len(b)] += a[i] * b_last;
FOR(i, len(b)) c[i + len(a)] += b[i] * a_last;
return c;
}
a.resize(sz), b.resize(sz);
bool same = a == b;
ntt(a, 0);
if (same) {
b = a;
} else {
ntt(b, 0);
}
FOR(i, sz) a[i] *= b[i];
ntt(a, 1);
a.resize(n + m - 1);
return a;
}
template <typename mint>
vc<mint> convolution(const vc<mint> &a, const vc<mint> &b) {
int n = len(a), m = len(b);
if (!n || !m) return {};
if (min(n, m) <= 50) return convolution_karatsuba<mint>(a, b);
return convolution_ntt(a, b);
}
// Input: f(0), ..., f(n-1) and c. Return: f(c)
template <typename T>
T lagrange_interpolate_iota(vc<T> &f, T c) {
int n = len(f);
if (int(c.val) < n) return f[c.val];
auto a = f;
FOR(i, n) {
a[i] = a[i] * fact_inv<T>(i) * fact_inv<T>(n - 1 - i);
if ((n - 1 - i) & 1) a[i] = -a[i];
}
vc<T> lp(n + 1), rp(n + 1);
lp[0] = rp[n] = 1;
FOR(i, n) lp[i + 1] = lp[i] * (c - i);
FOR_R(i, n) rp[i] = rp[i + 1] * (c - i);
T ANS = 0;
FOR(i, n) ANS += a[i] * lp[i] * rp[i + 1];
return ANS;
}
// Input: f(0), ..., f(n-1) and c, m
// Return: f(c), f(c+1), ..., f(c+m-1)
// Complexity: M(n, n + m)
template <typename mint>
vc<mint> lagrange_interpolate_iota(vc<mint> &f, mint c, int m) {
if (m <= 60) {
vc<mint> ANS(m);
FOR(i, m) ANS[i] = lagrange_interpolate_iota(f, c + mint(i));
return ANS;
}
ll n = len(f);
auto a = f;
FOR(i, n) {
a[i] = a[i] * fact_inv<mint>(i) * fact_inv<mint>(n - 1 - i);
if ((n - 1 - i) & 1) a[i] = -a[i];
}
// x = c, c+1, ... に対して a0/x + a1/(x-1) + ... を求めておく
vc<mint> b(n + m - 1);
FOR(i, n + m - 1) b[i] = mint(1) / (c + mint(i - n + 1));
a = convolution(a, b);
Sliding_Window_Aggregation<Monoid_Mul<mint>> swag;
vc<mint> ANS(m);
ll L = 0, R = 0;
FOR(i, m) {
while (L < i) { swag.pop(), ++L; }
while (R - L < n) { swag.push(c + mint((R++) - n + 1)); }
auto coef = swag.prod();
if (coef == 0) {
ANS[i] = f[(c + i).val];
} else {
ANS[i] = a[i + n - 1] * coef;
}
}
return ANS;
}
template <typename T>
vc<vc<T>> prefix_product_of_poly_matrix(vc<vc<vc<T>>> &A, ll k) {
int n = len(A);
using MAT = vc<vc<T>>;
auto shift = [&](vc<MAT> &G, T x) -> vc<MAT> {
int d = len(G);
vvv(T, H, d, n, n);
FOR(i, n) FOR(j, n) {
vc<T> g(d);
FOR(l, d) g[l] = G[l][i][j];
auto h = lagrange_interpolate_iota(g, x, d);
FOR(l, d) H[l][i][j] = h[l];
}
return H;
};
auto evaluate = [&](vc<T> &f, T x) -> T {
T res = 0;
T p = 1;
FOR(i, len(f)) {
res += f[i] * p;
p *= x;
}
return res;
};
ll deg = 1;
FOR(i, n) FOR(j, n) deg = max(deg, len(A[i][j]) - 1);
vc<MAT> G(deg + 1);
ll v = 1;
while (deg * v * v < k) v *= 2;
T iv = T(1) / T(v);
FOR(i, len(G)) {
T x = T(v) * T(i);
vv(T, mat, n, n);
FOR(j, n) FOR(k, n) mat[j][k] = evaluate(A[j][k], x);
G[i] = mat;
}
for (ll w = 1; w != v; w *= 2) {
T W = w;
auto G1 = shift(G, W * iv);
auto G2 = shift(G, (W * T(deg) * T(v) + T(v)) * iv);
auto G3 = shift(G, (W * T(deg) * T(v) + T(v) + W) * iv);
FOR(i, w * deg + 1) {
G[i] = matrix_mul(G1[i], G[i]);
G2[i] = matrix_mul(G3[i], G2[i]);
}
copy(G2.begin(), G2.end() - 1, back_inserter(G));
}
vv(T, res, n, n);
FOR(i, n) res[i][i] = 1;
ll i = 0;
while (i + v <= k) res = matrix_mul(G[i / v], res), i += v;
while (i < k) {
vv(T, mat, n, n);
FOR(j, n) FOR(k, n) mat[j][k] = evaluate(A[j][k], i);
res = matrix_mul(mat, res);
++i;
}
return res;
}
template <typename T>
T prefix_product_of_poly(vc<T> &f, ll k) {
vc<vc<vc<T>>> A(1);
A[0].resize(1);
A[0][0] = f;
auto res = prefix_product_of_poly_matrix(A, k);
return res[0][0];
}
using mint = modint998;
mint fact(const int n) {
vc<mint> f = {1, 1};
return prefix_product_of_poly(f, n);
}
// https://ferin-tech.hatenablog.com/entry/2018/01/17/010829
#define __USE_MINGW_ANSI_STDIO 0
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define int ll
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef pair<int, int> PII;
#define IN(a, b, x) (a<=x&&x<b)
#define PB push_back
const ll LLINF = (1LL<<60);
const int INF = (1LL<<30);
const int MOD = 1000000007;
template <typename T> T &chmin(T &a, const T &b) { return a = min(a, b); }
template <typename T> T &chmax(T &a, const T &b) { return a = max(a, b); }
template<class S,class T>
ostream &operator <<(ostream& out,const pair<S,T>& a){
out<<'('<<a.first<<','<<a.second<<')';
return out;
}
int dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};
// ax + by = gcd(a, b) となる {x, y, gcd(a, b)} を返す
// O(log(min(a, b)))
ll extgcd(ll a, ll b, ll &x, ll &y) {
ll g = a; x = 1, y = 0;
if(b != 0) g = extgcd(b, a%b, y, x), y -= (a/b) * x;
return g;
}
// a^-1 mod n を返す 存在しなければ-1
// O(log(n))
ll inv(ll a, ll n) {
ll s, t;
extgcd(a, n, s, t);
return (n+s) % n;
}
// 二分累乗法 x^e % mod O(log(e))
ll binpow(ll x, ll e, ll mod) {
ll a = 1, p = x;
while(e > 0) {
if(e%2 == 0) {p = (p*p) % mod; e /= 2;}
else {a = (a*p) % mod; e--;}
}
return a % mod;
}
// x = a1 mod m1, x2 = a2 mod m2 を解く オーバーフローには注意
// O(log(min(m1, m2)))
pair<ll, ll> crt(ll a1, ll a2, ll m1, ll m2) {
auto normal = [](ll x, ll m) { return x>=-x ? x%m : m-(-x)%m; };
auto modmul = [&normal](ll a, ll b, ll m) { return normal(a, m)*normal(b, m)%m; };
ll k1, k2;
ll g = extgcd(m1, m2, k1, k2);
if(normal(a1, g) != normal(a2, g)) return {-1, -1};
ll l = m1 / g * m2;
ll x = a1 + modmul(modmul((a2-a1)/g, k1, l), m1, l);
return {x, l};
}
pair<ll, ll> crt(vector<ll> a, vector<ll> m) {
ll mod = 1, ans = 0;
int n = a.size();
for (int i = 0; i < n; ++i) {
tie(ans, mod) = crt(ans, a[i], mod, m[i]);
if(ans == -1) return {-1, -1};
}
return {ans, mod};
}
ll C(ll n, ll r, ll p, ll q) {
if(n < 0 || r < 0 || r > n) return 0;
// pr = p^q
int pr = 1;
for (int i = 0; i < q; ++i) pr *= p;
ll z = n-r;
int e0 = 0;
for(ll u=n/p;u;u/=p) e0 += u;
for(ll u=r/p;u;u/=p) e0 -= u;
for(ll u=z/p;u;u/=p) e0 -= u;
int em = 0;
for(ll u=n/pr;u;u/=p) em += u;
for(ll u=r/pr;u;u/=p) em -= u;
for(ll u=z/pr;u;u/=p) em -= u;
ll ret = 1;
while(n > 0) {
const mint tmp = fact(n%pr) / fact(r%pr) / fact(z%pr);
ret = ret * ll{tmp.val} % pr;
n /= p; r /= p; z /= p;
}
(ret *= binpow(p, e0, pr)) %= pr;
if(!(p==2 && q >= 3) && em%2) ret = (pr-ret) % pr;
return ret;
}
ll func(ll n, ll r, ll mod) {
ll x = mod;
vector<ll> a, m;
a.PB(C(n, r, mod, 1));
m.PB(mod);
return crt(a, m).first;
}
signed main() {
int n, m; cin >> n >> m;
cout << func(n, m, 998244353) << '\n';
return 0;
}