#include #include using namespace std; using namespace atcoder; typedef long long ll; typedef unsigned long long ull; typedef long double ld; #define rep(i, n) for (ll i = 0; i < (ll)(n); i++) #define rrep(i,start,end) for (ll i = start;i >= (ll)(end);i--) #define repn(i,end) for(ll i = 0; i <= (ll)(end); i++) #define reps(i,start,end) for(ll i = start; i < (ll)(end); i++) #define repsn(i,start,end) for(ll i = start; i <= (ll)(end); i++) #define each(p,a) for(auto &p:a) typedef vector vll; typedef vector> vpll; typedef vector>> vvpll; typedef vector> vvll; typedef vector>> vvvll; typedef set sll; typedef map mpll; typedef pair pll; typedef tuple tpl3; typedef tuple tpl4; typedef tuple tpl5; typedef tuple tpl6; #define LL(...) ll __VA_ARGS__; input(__VA_ARGS__) #define LD(...) ld __VA_ARGS__; input(__VA_ARGS__) #define Str(...) string __VA_ARGS__; input(__VA_ARGS__) #define Ch(...) char __VA_ARGS__; input(__VA_ARGS__) #define all(a) (a).begin(),(a).end() #define UNIQUE(v) v.erase( unique(v.begin(), v.end()), v.end() ); #define sz(x) (ll)x.size() // << std::fixed << std::setprecision(10) const ll INF = 1LL << 60; const ld EPS = 1e-9; ll lceil(ll a,ll b){if(a%b==0){return a/b;}if(a>=0){return (a/b)+1;}else{return -((-a)/b);}} ll lfloor(ll a,ll b){if(a%b==0){return a/b;}if(a>=0){return (a/b);}else{return -((-a)/b)-1;}} inline ll positive_mod(ll a,ll m){return (a % m + m)%m;} inline ll popcnt(ull a){ return __builtin_popcountll(a);} //0indexed inline ll topbit(ll a){assert(a != 0);return 63 - __builtin_clzll(a);} inline ll smlbit(ll a){assert(a != 0);return __builtin_ctzll(a);} 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;} template std::istream &operator>>(std::istream&is,std::vector&v){for(T &in:v){is>>in;}return is;} template std::ostream &operator<<(std::ostream&os,const std::vector&v){for(auto it=std::begin(v);it!=std::end(v);){os<<*it<<((++it)!=std::end(v)?" ":"");}return os;} templatestd::ostream &operator<< (std::ostream &os, std::pair p){os << "{" << p.first << "," << p.second << "}";return os;} templatevoid input(T&... a){(cin >> ... >> a);} void print(){cout << endl;} templatevoid print(const T& a, const Ts&... b){cout << a;((cout << ' ' << b), ...);cout << endl;} template void pspace(const T& a){ cout << a << ' ';} void perr(){cerr << endl;} templatevoid perr(const T& a, const Ts&... b){cerr << a;((cerr << ' ' << b), ...);cerr << endl;} void yes(bool i = true){ return print(i?"yes":"no"); } void Yes(bool i = true){ return print(i?"Yes":"No"); } void YES(bool i = true){ return print(i?"YES":"NO"); } template vector &operator++(vector &v) {for(auto &e : v) e++;return v;} template vector operator++(vector &v, signed) {auto res = v;for(auto &e : v) e++;return res;} template vector &operator--(vector &v) {for(auto &e : v) e--;return v;} template vector operator--(vector &v, signed) {auto res = v;for(auto &e : v) e--;return res;} //grid探索用 vector _ta = {0,0,1,-1,1,1,-1,-1}; vector _yo = {1,-1,0,0,1,-1,1,-1}; bool isin(ll now_i,ll now_j,ll h,ll w){return (0<=now_i && now_i < h && 0 <= now_j && now_j < w);} ll lpow(ll x,ll n){ll ans = 1;while(n >0){if(n & 1)ans *= x;x *= x;n >>= 1;}return ans;} ll Modlpow(ll x,ll n,ll m){ll ans = 1;ll a = x%m;while(n >0){if(n & 1){ans *= a;ans%= m;}a *= a;a %= m;n >>= 1;}return ans;} const ll MOD9 = 998244353LL; const ll MOD10 = 1000000007LL; // ref https://drken1215.hatenablog.com/entry/2022/03/29/190000 // modint template struct Fp { long long val; constexpr Fp(long long v = 0) noexcept : val(v % MOD) { if (val < 0) val += MOD; } constexpr int getmod() const { return MOD; } constexpr Fp operator - () const noexcept { return val ? MOD - val : 0; } constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; } constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; } constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; } constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; } constexpr Fp& operator += (const Fp& r) noexcept { val += r.val; if (val >= MOD) val -= MOD; return *this; } constexpr Fp& operator -= (const Fp& r) noexcept { val -= r.val; if (val < 0) val += MOD; return *this; } constexpr Fp& operator *= (const Fp& r) noexcept { val = val * r.val % MOD; return *this; } constexpr Fp& operator /= (const Fp& r) noexcept { long long a = r.val, b = MOD, u = 1, v = 0; while (b) { long long t = a / b; a -= t * b, swap(a, b); u -= t * v, swap(u, v); } val = val * u % MOD; if (val < 0) val += MOD; return *this; } constexpr bool operator == (const Fp& r) const noexcept { return this->val == r.val; } constexpr bool operator != (const Fp& r) const noexcept { return this->val != r.val; } friend constexpr istream& operator >> (istream& is, Fp& x) noexcept { is >> x.val; x.val %= MOD; if (x.val < 0) x.val += MOD; return is; } friend constexpr ostream& operator << (ostream& os, const Fp& x) noexcept { return os << x.val; } friend constexpr Fp modpow(const Fp& r, long long n) noexcept { if (n == 0) return 1; if (n < 0) return modpow(modinv(r), -n); auto t = modpow(r, n / 2); t = t * t; if (n & 1) t = t * r; return t; } friend constexpr Fp modinv(const Fp& r) noexcept { long long a = r.val, b = MOD, u = 1, v = 0; while (b) { long long t = a / b; a -= t * b, swap(a, b); u -= t * v, swap(u, v); } return Fp(u); } }; namespace NTT { long long modpow(long long a, long long n, int mod) { long long res = 1; while (n > 0) { if (n & 1) res = res * a % mod; a = a * a % mod; n >>= 1; } return res; } long long modinv(long long a, int mod) { long long b = mod, u = 1, v = 0; while (b) { long long t = a / b; a -= t * b, swap(a, b); u -= t * v, swap(u, v); } u %= mod; if (u < 0) u += mod; return u; } int calc_primitive_root(int mod) { if (mod == 2) return 1; if (mod == 167772161) return 3; if (mod == 469762049) return 3; if (mod == 754974721) return 11; if (mod == 998244353) return 3; int divs[20] = {}; divs[0] = 2; int cnt = 1; long long x = (mod - 1) / 2; while (x % 2 == 0) x /= 2; for (long long i = 3; i * i <= x; i += 2) { if (x % i == 0) { divs[cnt++] = i; while (x % i == 0) x /= i; } } if (x > 1) divs[cnt++] = x; for (int g = 2;; g++) { bool ok = true; for (int i = 0; i < cnt; i++) { if (modpow(g, (mod - 1) / divs[i], mod) == 1) { ok = false; break; } } if (ok) return g; } } int get_fft_size(int N, int M) { int size_a = 1, size_b = 1; while (size_a < N) size_a <<= 1; while (size_b < M) size_b <<= 1; return max(size_a, size_b) << 1; } // number-theoretic transform template void trans(vector& v, bool inv = false) { if (v.empty()) return; int N = (int)v.size(); int MOD = v[0].getmod(); int PR = calc_primitive_root(MOD); static bool first = true; static vector vbw(30), vibw(30); if (first) { first = false; for (int k = 0; k < 30; ++k) { vbw[k] = modpow(PR, (MOD - 1) >> (k + 1), MOD); vibw[k] = modinv(vbw[k], MOD); } } for (int i = 0, j = 1; j < N - 1; j++) { for (int k = N >> 1; k > (i ^= k); k >>= 1); if (i > j) swap(v[i], v[j]); } for (int k = 0, t = 2; t <= N; ++k, t <<= 1) { long long bw = vbw[k]; if (inv) bw = vibw[k]; for (int i = 0; i < N; i += t) { mint w = 1; for (int j = 0; j < t/2; ++j) { int j1 = i + j, j2 = i + j + t/2; mint c1 = v[j1], c2 = v[j2] * w; v[j1] = c1 + c2; v[j2] = c1 - c2; w *= bw; } } } if (inv) { long long invN = modinv(N, MOD); for (int i = 0; i < N; ++i) v[i] = v[i] * invN; } } // for garner static constexpr int MOD0 = 754974721; static constexpr int MOD1 = 167772161; static constexpr int MOD2 = 469762049; using mint0 = Fp; using mint1 = Fp; using mint2 = Fp; static const mint1 imod0 = 95869806; // modinv(MOD0, MOD1); static const mint2 imod1 = 104391568; // modinv(MOD1, MOD2); static const mint2 imod01 = 187290749; // imod1 / MOD0; // small case (T = mint, long long) template vector naive_mul (const vector& A, const vector& B) { if (A.empty() || B.empty()) return {}; int N = (int)A.size(), M = (int)B.size(); vector res(N + M - 1); for (int i = 0; i < N; ++i) for (int j = 0; j < M; ++j) res[i + j] += A[i] * B[j]; return res; } // mint template vector mul (const vector& A, const vector& B) { if (A.empty() || B.empty()) return {}; int N = (int)A.size(), M = (int)B.size(); if (min(N, M) < 30) return naive_mul(A, B); int MOD = A[0].getmod(); int size_fft = get_fft_size(N, M); if (MOD == 998244353) { vector a(size_fft), b(size_fft), c(size_fft); for (int i = 0; i < N; ++i) a[i] = A[i]; for (int i = 0; i < M; ++i) b[i] = B[i]; trans(a), trans(b); vector res(size_fft); for (int i = 0; i < size_fft; ++i) res[i] = a[i] * b[i]; trans(res, true); res.resize(N + M - 1); return res; } vector a0(size_fft, 0), b0(size_fft, 0), c0(size_fft, 0); vector a1(size_fft, 0), b1(size_fft, 0), c1(size_fft, 0); vector a2(size_fft, 0), b2(size_fft, 0), c2(size_fft, 0); for (int i = 0; i < N; ++i) a0[i] = A[i].val, a1[i] = A[i].val, a2[i] = A[i].val; for (int i = 0; i < M; ++i) b0[i] = B[i].val, b1[i] = B[i].val, b2[i] = B[i].val; trans(a0), trans(a1), trans(a2), trans(b0), trans(b1), trans(b2); for (int i = 0; i < size_fft; ++i) { c0[i] = a0[i] * b0[i]; c1[i] = a1[i] * b1[i]; c2[i] = a2[i] * b2[i]; } trans(c0, true), trans(c1, true), trans(c2, true); static const mint mod0 = MOD0, mod01 = mod0 * MOD1; vector res(N + M - 1); for (int i = 0; i < N + M - 1; ++i) { int y0 = c0[i].val; int y1 = (imod0 * (c1[i] - y0)).val; int y2 = (imod01 * (c2[i] - y0) - imod1 * y1).val; res[i] = mod01 * y2 + mod0 * y1 + y0; } return res; } // long long vector mul_ll (const vector& A, const vector& B) { if (A.empty() || B.empty()) return {}; int N = (int)A.size(), M = (int)B.size(); if (min(N, M) < 30) return naive_mul(A, B); int size_fft = get_fft_size(N, M); vector a0(size_fft, 0), b0(size_fft, 0), c0(size_fft, 0); vector a1(size_fft, 0), b1(size_fft, 0), c1(size_fft, 0); vector a2(size_fft, 0), b2(size_fft, 0), c2(size_fft, 0); for (int i = 0; i < N; ++i) a0[i] = A[i], a1[i] = A[i], a2[i] = A[i]; for (int i = 0; i < M; ++i) b0[i] = B[i], b1[i] = B[i], b2[i] = B[i]; trans(a0), trans(a1), trans(a2), trans(b0), trans(b1), trans(b2); for (int i = 0; i < size_fft; ++i) { c0[i] = a0[i] * b0[i]; c1[i] = a1[i] * b1[i]; c2[i] = a2[i] * b2[i]; } trans(c0, true), trans(c1, true), trans(c2, true); static const long long mod0 = MOD0, mod01 = mod0 * MOD1; vector res(N + M - 1); for (int i = 0; i < N + M - 1; ++i) { int y0 = c0[i].val; int y1 = (imod0 * (c1[i] - y0)).val; int y2 = (imod01 * (c2[i] - y0) - imod1 * y1).val; res[i] = mod01 * y2 + mod0 * y1 + y0; } return res; } }; // Binomial Coefficient template struct BiCoef { vector fact_, inv_, finv_; constexpr BiCoef() {} constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) { init(n); } constexpr void init(int n) noexcept { fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1); int MOD = fact_[0].getmod(); for(int i = 2; i < n; i++){ fact_[i] = fact_[i-1] * i; inv_[i] = -inv_[MOD%i] * (MOD/i); finv_[i] = finv_[i-1] * inv_[i]; } } constexpr T com(int n, int k) const noexcept { if (n < k || n < 0 || k < 0) return 0; return fact_[n] * finv_[k] * finv_[n-k]; } constexpr T fact(int n) const noexcept { if (n < 0) return 0; return fact_[n]; } constexpr T inv(int n) const noexcept { if (n < 0) return 0; return inv_[n]; } constexpr T finv(int n) const noexcept { if (n < 0) return 0; return finv_[n]; } }; // Formal Power Series template struct FPS : vector { using vector::vector; // constructor FPS(const vector& r) : vector(r) {} // core operator inline FPS pre(int siz) const { return FPS(begin(*this), begin(*this) + min((int)this->size(), siz)); } inline FPS rev() const { FPS res = *this; reverse(begin(res), end(res)); return res; } inline FPS& normalize() { while (!this->empty() && this->back() == 0) this->pop_back(); return *this; } // basic operator inline FPS operator - () const noexcept { FPS res = (*this); for (int i = 0; i < (int)res.size(); ++i) res[i] = -res[i]; return res; } inline FPS operator + (const mint& v) const { return FPS(*this) += v; } inline FPS operator + (const FPS& r) const { return FPS(*this) += r; } inline FPS operator - (const mint& v) const { return FPS(*this) -= v; } inline FPS operator - (const FPS& r) const { return FPS(*this) -= r; } inline FPS operator * (const mint& v) const { return FPS(*this) *= v; } inline FPS operator * (const FPS& r) const { return FPS(*this) *= r; } inline FPS operator / (const mint& v) const { return FPS(*this) /= v; } inline FPS operator << (int x) const { return FPS(*this) <<= x; } inline FPS operator >> (int x) const { return FPS(*this) >>= x; } inline FPS& operator += (const mint& v) { if (this->empty()) this->resize(1); (*this)[0] += v; return *this; } inline FPS& operator += (const FPS& r) { if (r.size() > this->size()) this->resize(r.size()); for (int i = 0; i < (int)r.size(); ++i) (*this)[i] += r[i]; return this->normalize(); } inline FPS& operator -= (const mint& v) { if (this->empty()) this->resize(1); (*this)[0] -= v; return *this; } inline FPS& operator -= (const FPS& r) { if (r.size() > this->size()) this->resize(r.size()); for (int i = 0; i < (int)r.size(); ++i) (*this)[i] -= r[i]; return this->normalize(); } inline FPS& operator *= (const mint& v) { for (int i = 0; i < (int)this->size(); ++i) (*this)[i] *= v; return *this; } inline FPS& operator *= (const FPS& r) { return *this = NTT::mul((*this), r); } inline FPS& operator /= (const mint& v) { assert(v != 0); mint iv = modinv(v); for (int i = 0; i < (int)this->size(); ++i) (*this)[i] *= iv; return *this; } inline FPS& operator <<= (int x) { FPS res(x, 0); res.insert(res.end(), begin(*this), end(*this)); return *this = res; } inline FPS& operator >>= (int x) { FPS res; res.insert(res.end(), begin(*this) + x, end(*this)); return *this = res; } inline mint eval(const mint& v){ mint res = 0; for (int i = (int)this->size()-1; i >= 0; --i) { res *= v; res += (*this)[i]; } return res; } inline friend FPS gcd(const FPS& f, const FPS& g) { if (g.empty()) return f; return gcd(g, f % g); } // advanced operation // df/dx inline friend FPS diff(const FPS& f) { int n = (int)f.size(); FPS res(n-1); for (int i = 1; i < n; ++i) res[i-1] = f[i] * i; return res; } // \int f dx inline friend FPS integrate(const FPS& f) { int n = (int)f.size(); FPS res(n+1, 0); for (int i = 0; i < n; ++i) res[i+1] = f[i] / (i+1); return res; } // inv(f), f[0] must not be 0 inline friend FPS inv(const FPS& f, int deg) { assert(f[0] != 0); if (deg < 0) deg = (int)f.size(); FPS res({mint(1) / f[0]}); for (int i = 1; i < deg; i <<= 1) { res = (res + res - res * res * f.pre(i << 1)).pre(i << 1); } res.resize(deg); return res; } inline friend FPS inv(const FPS& f) { return inv(f, f.size()); } // division, r must be normalized (r.back() must not be 0) inline FPS& operator /= (const FPS& r) { assert(!r.empty()); assert(r.back() != 0); this->normalize(); if (this->size() < r.size()) { this->clear(); return *this; } int need = (int)this->size() - (int)r.size() + 1; *this = ((*this).rev().pre(need) * inv(r.rev(), need)).pre(need).rev(); return *this; } inline FPS& operator %= (const FPS &r) { assert(!r.empty()); assert(r.back() != 0); this->normalize(); FPS q = (*this) / r; return *this -= q * r; } inline FPS operator / (const FPS& r) const { return FPS(*this) /= r; } inline FPS operator % (const FPS& r) const { return FPS(*this) %= r; } // log(f) = \int f'/f dx, f[0] must be 1 inline friend FPS log(const FPS& f, int deg) { assert(f[0] == 1); FPS res = integrate(diff(f) * inv(f, deg)); res.resize(deg); return res; } inline friend FPS log(const FPS& f) { return log(f, f.size()); } // exp(f), f[0] must be 0 inline friend FPS exp(const FPS& f, int deg) { assert(f[0] == 0); FPS res(1, 1); for (int i = 1; i < deg; i <<= 1) { res = res * (f.pre(i<<1) - log(res, i<<1) + 1).pre(i<<1); } res.resize(deg); return res; } inline friend FPS exp(const FPS& f) { return exp(f, f.size()); } // pow(f) = exp(e * log f) inline friend FPS pow(const FPS& f, long long e, int deg) { long long i = 0; while (i < (int)f.size() && f[i] == 0) ++i; if (i == (int)f.size()) return FPS(deg, 0); if (i * e >= deg) return FPS(deg, 0); mint k = f[i]; FPS res = exp(log((f >> i) / k, deg) * e, deg) * modpow(k, e) << (e * i); res.resize(deg); return res; } inline friend FPS pow(const FPS& f, long long e) { return pow(f, e, f.size()); } // sqrt(f), f[0] must be 1 inline friend FPS sqrt_base(const FPS& f, int deg) { assert(f[0] == 1); mint inv2 = mint(1) / 2; FPS res(1, 1); for (int i = 1; i < deg; i <<= 1) { res = (res + f.pre(i << 1) * inv(res, i << 1)).pre(i << 1); for (mint& x : res) x *= inv2; } res.resize(deg); return res; } inline friend FPS sqrt_base(const FPS& f) { return sqrt_base(f, f.size()); } }; // Bostan-Mori // find [x^N] P(x)/Q(x) // O(K log K log N), K = max(deg(P(x)), deg(Q(x))) template mint BostanMori(const FPS &P, const FPS &Q, long long N) { assert(!P.empty() && !Q.empty()); if (N == 0) return P[0] / Q[0]; FPS P2{P}, minusQ{Q}; for (int i = 1; i < (int)Q.size(); i += 2) { minusQ[i] = -minusQ[i]; } P2 *= minusQ; FPS Q2 = Q * minusQ; FPS S, T; if (N % 2 == 0) { for (int i = 0; i * 2 < (int)P2.size(); ++i) { S.emplace_back(P2[i * 2]); } } else { for (int i = 0; i * 2 + 1 < (int)P2.size(); ++i) { S.emplace_back(P2[i * 2 + 1]); } } for (int i = 0; i * 2 < (int)Q2.size(); ++i) { T.emplace_back(Q2[i * 2]); } return BostanMori(S, T, N >> 1); } int main(){ ios::sync_with_stdio(false);cin.tie(nullptr); using mint = Fp<1234567891>; LL(n,m); vll a(n);cin >> a; FPS ret = {1}; rep(i,n){ FPS tmp(a[i]+1); tmp[0] = 1; tmp[a[i]] = -1; ret = NTT::mul(ret,tmp); } FPS tp = {1}; mint ans = BostanMori(tp,ret,m); cout << ans.val << endl; }