#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 #include using namespace std; using lint = long long; using pint = pair; using plint = pair; struct fast_ios { fast_ios(){ cin.tie(nullptr), ios::sync_with_stdio(false), cout << fixed << setprecision(20); }; } fast_ios_; #define ALL(x) (x).begin(), (x).end() #define FOR(i, begin, end) for(int i=(begin),i##_end_=(end);i=i##_begin_;i--) #define REP(i, n) FOR(i,0,n) #define IREP(i, n) IFOR(i,0,n) template void ndarray(vector& vec, const V& val, int len) { vec.assign(len, val); } template void ndarray(vector& vec, const V& val, int len, Args... args) { vec.resize(len), for_each(begin(vec), end(vec), [&](T& v) { ndarray(v, val, args...); }); } template bool chmax(T &m, const T q) { return m < q ? (m = q, true) : false; } template bool chmin(T &m, const T q) { return m > q ? (m = q, true) : false; } int floor_lg(long long x) { return x <= 0 ? -1 : 63 - __builtin_clzll(x); } template pair operator+(const pair &l, const pair &r) { return make_pair(l.first + r.first, l.second + r.second); } template pair operator-(const pair &l, const pair &r) { return make_pair(l.first - r.first, l.second - r.second); } template vector sort_unique(vector vec) { sort(vec.begin(), vec.end()), vec.erase(unique(vec.begin(), vec.end()), vec.end()); return vec; } template int arglb(const std::vector &v, const T &x) { return std::distance(v.begin(), std::lower_bound(v.begin(), v.end(), x)); } template int argub(const std::vector &v, const T &x) { return std::distance(v.begin(), std::upper_bound(v.begin(), v.end(), x)); } template istream &operator>>(istream &is, vector &vec) { for (auto &v : vec) is >> v; return is; } template ostream &operator<<(ostream &os, const vector &vec) { os << '['; for (auto v : vec) os << v << ','; os << ']'; return os; } template ostream &operator<<(ostream &os, const array &arr) { os << '['; for (auto v : arr) os << v << ','; os << ']'; return os; } #if __cplusplus >= 201703L template istream &operator>>(istream &is, tuple &tpl) { std::apply([&is](auto &&... args) { ((is >> args), ...);}, tpl); return is; } template ostream &operator<<(ostream &os, const tuple &tpl) { os << '('; std::apply([&os](auto &&... args) { ((os << args << ','), ...);}, tpl); return os << ')'; } #endif template ostream &operator<<(ostream &os, const deque &vec) { os << "deq["; for (auto v : vec) os << v << ','; os << ']'; return os; } template ostream &operator<<(ostream &os, const set &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; } template ostream &operator<<(ostream &os, const unordered_set &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; } template ostream &operator<<(ostream &os, const multiset &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; } template ostream &operator<<(ostream &os, const unordered_multiset &vec) { os << '{'; for (auto v : vec) os << v << ','; os << '}'; return os; } template ostream &operator<<(ostream &os, const pair &pa) { os << '(' << pa.first << ',' << pa.second << ')'; return os; } template ostream &operator<<(ostream &os, const map &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; } template ostream &operator<<(ostream &os, const unordered_map &mp) { os << '{'; for (auto v : mp) os << v.first << "=>" << v.second << ','; os << '}'; return os; } #ifdef HITONANODE_LOCAL const string COLOR_RESET = "\033[0m", BRIGHT_GREEN = "\033[1;32m", BRIGHT_RED = "\033[1;31m", BRIGHT_CYAN = "\033[1;36m", NORMAL_CROSSED = "\033[0;9;37m", RED_BACKGROUND = "\033[1;41m", NORMAL_FAINT = "\033[0;2m"; #define dbg(x) cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << endl #define dbgif(cond, x) ((cond) ? cerr << BRIGHT_CYAN << #x << COLOR_RESET << " = " << (x) << NORMAL_FAINT << " (L" << __LINE__ << ") " << __FILE__ << COLOR_RESET << endl : cerr) #else #define dbg(x) (x) #define dbgif(cond, x) 0 #endif #include #include #include template struct ModInt { #if __cplusplus >= 201402L #define MDCONST constexpr #else #define MDCONST #endif using lint = long long; MDCONST static int mod() { return md; } static int get_primitive_root() { static int primitive_root = 0; if (!primitive_root) { primitive_root = [&]() { std::set fac; int v = md - 1; for (lint i = 2; i * i <= v; i++) while (v % i == 0) fac.insert(i), v /= i; if (v > 1) fac.insert(v); for (int g = 1; g < md; g++) { bool ok = true; for (auto i : fac) if (ModInt(g).pow((md - 1) / i) == 1) { ok = false; break; } if (ok) return g; } return -1; }(); } return primitive_root; } int val; MDCONST ModInt() : val(0) {} MDCONST ModInt &_setval(lint v) { return val = (v >= md ? v - md : v), *this; } MDCONST ModInt(lint v) { _setval(v % md + md); } MDCONST explicit operator bool() const { return val != 0; } MDCONST ModInt operator+(const ModInt &x) const { return ModInt()._setval((lint)val + x.val); } MDCONST ModInt operator-(const ModInt &x) const { return ModInt()._setval((lint)val - x.val + md); } MDCONST ModInt operator*(const ModInt &x) const { return ModInt()._setval((lint)val * x.val % md); } MDCONST ModInt operator/(const ModInt &x) const { return ModInt()._setval((lint)val * x.inv() % md); } MDCONST ModInt operator-() const { return ModInt()._setval(md - val); } MDCONST ModInt &operator+=(const ModInt &x) { return *this = *this + x; } MDCONST ModInt &operator-=(const ModInt &x) { return *this = *this - x; } MDCONST ModInt &operator*=(const ModInt &x) { return *this = *this * x; } MDCONST ModInt &operator/=(const ModInt &x) { return *this = *this / x; } friend MDCONST ModInt operator+(lint a, const ModInt &x) { return ModInt()._setval(a % md + x.val); } friend MDCONST ModInt operator-(lint a, const ModInt &x) { return ModInt()._setval(a % md - x.val + md); } friend MDCONST ModInt operator*(lint a, const ModInt &x) { return ModInt()._setval(a % md * x.val % md); } friend MDCONST ModInt operator/(lint a, const ModInt &x) { return ModInt()._setval(a % md * x.inv() % md); } MDCONST bool operator==(const ModInt &x) const { return val == x.val; } MDCONST bool operator!=(const ModInt &x) const { return val != x.val; } MDCONST bool operator<(const ModInt &x) const { return val < x.val; } // To use std::map friend std::istream &operator>>(std::istream &is, ModInt &x) { lint t; return is >> t, x = ModInt(t), is; } MDCONST friend std::ostream &operator<<(std::ostream &os, const ModInt &x) { return os << x.val; } MDCONST ModInt pow(lint n) const { ModInt ans = 1, tmp = *this; while (n) { if (n & 1) ans *= tmp; tmp *= tmp, n >>= 1; } return ans; } static std::vector facs, facinvs, invs; MDCONST static void _precalculation(int N) { int l0 = facs.size(); if (N > md) N = md; if (N <= l0) return; facs.resize(N), facinvs.resize(N), invs.resize(N); for (int i = l0; i < N; i++) facs[i] = facs[i - 1] * i; facinvs[N - 1] = facs.back().pow(md - 2); for (int i = N - 2; i >= l0; i--) facinvs[i] = facinvs[i + 1] * (i + 1); for (int i = N - 1; i >= l0; i--) invs[i] = facinvs[i] * facs[i - 1]; } MDCONST lint inv() const { if (this->val < std::min(md >> 1, 1 << 21)) { while (this->val >= int(facs.size())) _precalculation(facs.size() * 2); return invs[this->val].val; } else { return this->pow(md - 2).val; } } MDCONST ModInt fac() const { while (this->val >= int(facs.size())) _precalculation(facs.size() * 2); return facs[this->val]; } MDCONST ModInt facinv() const { while (this->val >= int(facs.size())) _precalculation(facs.size() * 2); return facinvs[this->val]; } MDCONST ModInt doublefac() const { lint k = (this->val + 1) / 2; return (this->val & 1) ? ModInt(k * 2).fac() / (ModInt(2).pow(k) * ModInt(k).fac()) : ModInt(k).fac() * ModInt(2).pow(k); } MDCONST ModInt nCr(const ModInt &r) const { return (this->val < r.val) ? 0 : this->fac() * (*this - r).facinv() * r.facinv(); } MDCONST ModInt nPr(const ModInt &r) const { return (this->val < r.val) ? 0 : this->fac() * (*this - r).facinv(); } ModInt sqrt() const { if (val == 0) return 0; if (md == 2) return val; if (pow((md - 1) / 2) != 1) return 0; ModInt b = 1; while (b.pow((md - 1) / 2) == 1) b += 1; int e = 0, m = md - 1; while (m % 2 == 0) m >>= 1, e++; ModInt x = pow((m - 1) / 2), y = (*this) * x * x; x *= (*this); ModInt z = b.pow(m); while (y != 1) { int j = 0; ModInt t = y; while (t != 1) j++, t *= t; z = z.pow(1LL << (e - j - 1)); x *= z, z *= z, y *= z; e = j; } return ModInt(std::min(x.val, md - x.val)); } }; template std::vector> ModInt::facs = {1}; template std::vector> ModInt::facinvs = {1}; template std::vector> ModInt::invs = {0}; using mint = ModInt<998244353>; // Integer convolution for arbitrary mod // with NTT (and Garner's algorithm) for ModInt / ModIntRuntime class. // We skip Garner's algorithm if `skip_garner` is true or mod is in `nttprimes`. // input: a (size: n), b (size: m) // return: vector (size: n + m - 1) template std::vector nttconv(std::vector a, std::vector b, bool skip_garner); constexpr int nttprimes[3] = {998244353, 167772161, 469762049}; // Integer FFT (Fast Fourier Transform) for ModInt class // (Also known as Number Theoretic Transform, NTT) // is_inverse: inverse transform // ** Input size must be 2^n ** template void ntt(std::vector &a, bool is_inverse = false) { int n = a.size(); if (n == 1) return; static const int mod = MODINT::mod(); static const MODINT root = MODINT::get_primitive_root(); assert(__builtin_popcount(n) == 1 and (mod - 1) % n == 0); static std::vector w{1}, iw{1}; for (int m = w.size(); m < n / 2; m *= 2) { MODINT dw = root.pow((mod - 1) / (4 * m)), dwinv = 1 / dw; w.resize(m * 2), iw.resize(m * 2); for (int i = 0; i < m; i++) w[m + i] = w[i] * dw, iw[m + i] = iw[i] * dwinv; } if (!is_inverse) { for (int m = n; m >>= 1;) { for (int s = 0, k = 0; s < n; s += 2 * m, k++) { for (int i = s; i < s + m; i++) { MODINT x = a[i], y = a[i + m] * w[k]; a[i] = x + y, a[i + m] = x - y; } } } } else { for (int m = 1; m < n; m *= 2) { for (int s = 0, k = 0; s < n; s += 2 * m, k++) { for (int i = s; i < s + m; i++) { MODINT x = a[i], y = a[i + m]; a[i] = x + y, a[i + m] = (x - y) * iw[k]; } } } int n_inv = MODINT(n).inv(); for (auto &v : a) v *= n_inv; } } template std::vector> nttconv_(const std::vector &a, const std::vector &b) { int sz = a.size(); assert(a.size() == b.size() and __builtin_popcount(sz) == 1); std::vector> ap(sz), bp(sz); for (int i = 0; i < sz; i++) ap[i] = a[i], bp[i] = b[i]; ntt(ap, false); if (a == b) bp = ap; else ntt(bp, false); for (int i = 0; i < sz; i++) ap[i] *= bp[i]; ntt(ap, true); return ap; } long long garner_ntt_(int r0, int r1, int r2, int mod) { using mint2 = ModInt; static const long long m01 = 1LL * nttprimes[0] * nttprimes[1]; static const long long m0_inv_m1 = ModInt(nttprimes[0]).inv(); static const long long m01_inv_m2 = mint2(m01).inv(); int v1 = (m0_inv_m1 * (r1 + nttprimes[1] - r0)) % nttprimes[1]; auto v2 = (mint2(r2) - r0 - mint2(nttprimes[0]) * v1) * m01_inv_m2; return (r0 + 1LL * nttprimes[0] * v1 + m01 % mod * v2.val) % mod; } template std::vector nttconv(std::vector a, std::vector b, bool skip_garner) { if (a.empty() or b.empty()) return {}; int sz = 1, n = a.size(), m = b.size(); while (sz < n + m) sz <<= 1; if (sz <= 16) { std::vector ret(n + m - 1); for (int i = 0; i < n; i++) { for (int j = 0; j < m; j++) ret[i + j] += a[i] * b[j]; } return ret; } int mod = MODINT::mod(); if (skip_garner or std::find(std::begin(nttprimes), std::end(nttprimes), mod) != std::end(nttprimes)) { a.resize(sz), b.resize(sz); if (a == b) { ntt(a, false); b = a; } else { ntt(a, false), ntt(b, false); } for (int i = 0; i < sz; i++) a[i] *= b[i]; ntt(a, true); a.resize(n + m - 1); } else { std::vector ai(sz), bi(sz); for (int i = 0; i < n; i++) ai[i] = a[i].val; for (int i = 0; i < m; i++) bi[i] = b[i].val; auto ntt0 = nttconv_(ai, bi); auto ntt1 = nttconv_(ai, bi); auto ntt2 = nttconv_(ai, bi); a.resize(n + m - 1); for (int i = 0; i < n + m - 1; i++) a[i] = garner_ntt_(ntt0[i].val, ntt1[i].val, ntt2[i].val, mod); } return a; } template std::vector nttconv(const std::vector &a, const std::vector &b) { return nttconv(a, b, false); } // Formal Power Series (形式的冪級数) based on ModInt / ModIntRuntime // Reference: https://ei1333.github.io/luzhiled/snippets/math/formal-power-series.html template struct FormalPowerSeries : vector { using vector::vector; using P = FormalPowerSeries; void shrink() { while (this->size() and this->back() == T(0)) this->pop_back(); } P operator+(const P &r) const { return P(*this) += r; } P operator+(const T &v) const { return P(*this) += v; } P operator-(const P &r) const { return P(*this) -= r; } P operator-(const T &v) const { return P(*this) -= v; } P operator*(const P &r) const { return P(*this) *= r; } P operator*(const T &v) const { return P(*this) *= v; } P operator/(const P &r) const { return P(*this) /= r; } P operator/(const T &v) const { return P(*this) /= v; } P operator%(const P &r) const { return P(*this) %= r; } P &operator+=(const P &r) { if (r.size() > this->size()) this->resize(r.size()); for (int i = 0; i < (int)r.size(); i++) (*this)[i] += r[i]; shrink(); return *this; } P &operator+=(const T &v) { if (this->empty()) this->resize(1); (*this)[0] += v; shrink(); return *this; } P &operator-=(const P &r) { if (r.size() > this->size()) this->resize(r.size()); for (int i = 0; i < (int)r.size(); i++) (*this)[i] -= r[i]; shrink(); return *this; } P &operator-=(const T &v) { if (this->empty()) this->resize(1); (*this)[0] -= v; shrink(); return *this; } P &operator*=(const T &v) { for (auto &x : (*this)) x *= v; shrink(); return *this; } P &operator*=(const P &r) { if (this->empty() || r.empty()) this->clear(); else { auto ret = nttconv(*this, r); *this = P(ret.begin(), ret.end()); } return *this; } P &operator%=(const P &r) { *this -= *this / r * r; shrink(); return *this; } P operator-() const { P ret = *this; for (auto &v : ret) v = -v; return ret; } P &operator/=(const T &v) { assert(v != T(0)); for (auto &x : (*this)) x /= v; return *this; } P &operator/=(const P &r) { if (this->size() < r.size()) { this->clear(); return *this; } int n = (int)this->size() - r.size() + 1; return *this = (reversed().pre(n) * r.reversed().inv(n)).pre(n).reversed(n); } P pre(int sz) const { P ret(this->begin(), this->begin() + min((int)this->size(), sz)); ret.shrink(); return ret; } P operator>>(int sz) const { if ((int)this->size() <= sz) return {}; return P(this->begin() + sz, this->end()); } P operator<<(int sz) const { if (this->empty()) return {}; P ret(*this); ret.insert(ret.begin(), sz, T(0)); return ret; } P reversed(int deg = -1) const { assert(deg >= -1); P ret(*this); if (deg != -1) ret.resize(deg, T(0)); reverse(ret.begin(), ret.end()); ret.shrink(); return ret; } P differential() const { // formal derivative (differential) of f.p.s. const int n = (int)this->size(); P ret(max(0, n - 1)); for (int i = 1; i < n; i++) ret[i - 1] = (*this)[i] * T(i); return ret; } P integral() const { const int n = (int)this->size(); P ret(n + 1); ret[0] = T(0); for (int i = 0; i < n; i++) ret[i + 1] = (*this)[i] / T(i + 1); return ret; } P inv(int deg) const { assert(deg >= -1); assert(this->size() and ((*this)[0]) != T(0)); // Requirement: F(0) != 0 const int n = this->size(); if (deg == -1) deg = n; P ret({T(1) / (*this)[0]}); for (int i = 1; i < deg; i <<= 1) { ret = (ret + ret - ret * ret * pre(i << 1)).pre(i << 1); } ret = ret.pre(deg); ret.shrink(); return ret; } P log(int deg = -1) const { assert(deg >= -1); assert(this->size() and ((*this)[0]) == T(1)); // Requirement: F(0) = 1 const int n = (int)this->size(); if (deg == 0) return {}; if (deg == -1) deg = n; return (this->differential() * this->inv(deg)).pre(deg - 1).integral(); } P sqrt(int deg = -1) const { assert(deg >= -1); const int n = (int)this->size(); if (deg == -1) deg = n; if (this->empty()) return {}; if ((*this)[0] == T(0)) { for (int i = 1; i < n; i++) if ((*this)[i] != T(0)) { if ((i & 1) or deg - i / 2 <= 0) return {}; return (*this >> i).sqrt(deg - i / 2) << (i / 2); } return {}; } T sqrtf0 = (*this)[0].sqrt(); if (sqrtf0 == T(0)) return {}; P y = (*this) / (*this)[0], ret({T(1)}); T inv2 = T(1) / T(2); for (int i = 1; i < deg; i <<= 1) { ret = (ret + y.pre(i << 1) * ret.inv(i << 1)) * inv2; } return ret.pre(deg) * sqrtf0; } P exp(int deg = -1) const { assert(deg >= -1); assert(this->empty() or ((*this)[0]) == T(0)); // Requirement: F(0) = 0 const int n = (int)this->size(); if (deg == -1) deg = n; P ret({T(1)}); for (int i = 1; i < deg; i <<= 1) { ret = (ret * (pre(i << 1) + T(1) - ret.log(i << 1))).pre(i << 1); } return ret.pre(deg); } P pow(long long k, int deg = -1) const { assert(deg >= -1); const int n = (int)this->size(); if (deg == -1) deg = n; for (int i = 0; i < n; i++) { if ((*this)[i] != T(0)) { T rev = T(1) / (*this)[i]; P C = (*this) * rev, D(n - i); for (int j = i; j < n; j++) D[j - i] = C.coeff(j); D = (D.log(deg) * T(k)).exp(deg) * (*this)[i].pow(k); if (k * (i > 0) > deg or k * i > deg) return {}; P E(deg); long long S = i * k; for (int j = 0; j + S < deg and j < (int)D.size(); j++) E[j + S] = D[j]; E.shrink(); return E; } } return *this; } // Calculate f(X + c) from f(X), O(NlogN) P shift(T c) const { const int n = (int)this->size(); P ret = *this; for (int i = 0; i < n; i++) { ret[i] *= T(i).fac(); } reverse(ret.begin(), ret.end()); P exp_cx(n, 1); for (int i = 1; i < n; i++) { exp_cx[i] = exp_cx[i - 1] * c / i; } ret = (ret * exp_cx), ret.resize(n); reverse(ret.begin(), ret.end()); for (int i = 0; i < n; i++) { ret[i] /= T(i).fac(); } return ret; } T coeff(int i) const { if ((int)this->size() <= i or i < 0) return T(0); return (*this)[i]; } T eval(T x) const { T ret = 0, w = 1; for (auto &v : *this) ret += w * v, w *= x; return ret; } }; // multipoint polynomial evaluation // input: xs = [x_0, ..., x_{N - 1}]: points to evaluate // f = \sum_i^M f_i x^i // Complexity: O(N (lgN)^2) building, O(N (lgN)^2 + M lg M) evaluation template struct MultipointEvaluation { int nx; using polynomial = FormalPowerSeries; std::vector segtree; MultipointEvaluation(const std::vector &xs) : nx(xs.size()) { segtree.resize(nx * 2 - 1); for (int i = 0; i < nx; i++) { segtree[nx - 1 + i] = {-xs[i], 1}; } for (int i = nx - 2; i >= 0; i--) { segtree[i] = segtree[2 * i + 1] * segtree[2 * i + 2]; } } std::vector ret; void _eval_rec(polynomial f, int now) { f %= segtree[now]; if (now - (nx - 1) >= 0) { ret[now - (nx - 1)] = f.coeff(0); return; } _eval_rec(f, 2 * now + 1); _eval_rec(f, 2 * now + 2); } std::vector evaluate_polynomial(const polynomial &f) { ret.resize(nx); _eval_rec(f, 0); return ret; } std::vector evaluate_polynomial(const std::vector &f) { return evaluate_polynomial(polynomial(f.begin(), f.end())); } std::vector _interpolate_coeffs; polynomial _rec_interpolation(int now, const std::vector &ys) const { int i = now - (nx - 1); if (i >= 0) return {ys[i]}; auto retl = _rec_interpolation(2 * now + 1, ys); auto retr = _rec_interpolation(2 * now + 2, ys); return retl * segtree[2 * now + 2] + retr * segtree[2 * now + 1]; } std::vector polynomial_interpolation(std::vector ys) { assert(nx == int(ys.size())); if (_interpolate_coeffs.empty()) { _interpolate_coeffs = evaluate_polynomial(segtree[0].differential()); for (auto &x : _interpolate_coeffs) x = x.inv(); } for (int i = 0; i < nx; i++) ys[i] *= _interpolate_coeffs[i]; return _rec_interpolation(0, ys); } }; using fps = FormalPowerSeries; // x(1 + (x - 1)(1 + (x - 2)(... (x - (n - 1)(f))))) = gf + h pair rec(int n) { if (n == 1) return {{0, 1}, {1}}; int h = n / 2; auto [g0, h0] = rec(h); g0.resize(h + 2); h0.resize(h + 2); fps g1 = g0.shift(-(n - h)), h1 = h0.shift(-(n - h)); if (n % 2) { fps z{-h, 1}; g1 = g1 * z; h1 = h1 * z + mint(1); } auto g = g1 * g0; auto hret = g0 * h1 + h0; return {g, hret}; } int main() { int N, M; cin >> N >> M; vector A(M); cin >> A; mint ret = 0; FOR(k, 1, N + 1) { int a = *lower_bound(A.begin(), A.end(), k); ret += mint(N - k + 1).inv() * a; } cout << ret << '\n'; }