#include using namespace std; #include namespace mp = boost::multiprecision; #include using namespace atcoder; #pragma GCC optimize("O0") typedef long long int ll; typedef long double ld; const ll mod = 1e9+7; const ll INF = 1e18; #define rep(i,n) for (ll i = 0; i < (n); ++i) #define Rep(i,a,n) for (ll i = (a); i < (n); ++i) #define All(a) (a).begin(),(a).end() #define Pi acos(-1) using Graph = vector>; using V = vector; using P = pair; templatebool chmax(T &a, const T &b) { if (abool chmin(T &a, const T &b) { if (b struct FormalPowerSeries : vector { using vector::vector; using vector::operator=; using F = FormalPowerSeries; F operator-() const { F res(*this); for (auto &e : res) e = -e; return res; } F &operator*=(const T &g) { for (auto &e : *this) e *= g; return *this; } F &operator/=(const T &g) { assert(g != T(0)); *this *= g.inv(); return *this; } F &operator+=(const F &g) { ll n = (*this).size(), m = g.size(); rep(i, min(n, m)) (*this)[i] += g[i]; return *this; } F &operator-=(const F &g) { ll n = (*this).size(), m = g.size(); rep(i, min(n, m)) (*this)[i] -= g[i]; return *this; } F &operator<<=(const ll d) { ll n = (*this).size(); (*this).insert((*this).begin(), d, 0); (*this).resize(n); return *this; } F &operator>>=(const ll d) { ll n = (*this).size(); (*this).erase((*this).begin(), (*this).begin() + min(n, d)); (*this).resize(n); return *this; } F inv(ll d = -1) const { ll n = (*this).size(); assert(n != 0 && (*this)[0] != 0); if (d == -1) d = n; assert(d > 0); F res{(*this)[0].inv()}; while (res.size() < d) { ll m = size(res); F f(begin(*this), begin(*this) + min(n, 2*m)); F r(res); f.resize(2*m), internal::butterfly(f); r.resize(2*m), internal::butterfly(r); rep(i, 2*m) f[i] *= r[i]; internal::butterfly_inv(f); f.erase(f.begin(), f.begin() + m); f.resize(2*m), internal::butterfly(f); rep(i, 2*m) f[i] *= r[i]; internal::butterfly_inv(f); T iz = T(2*m).inv(); iz *= -iz; rep(i, m) f[i] *= iz; res.insert(res.end(), f.begin(), f.begin() + m); } return {res.begin(), res.begin() + d}; } // fast: FMT-friendly modulus only F &operator*=(const F &g) { ll n = (*this).size(); *this = convolution(*this, g); (*this).resize(n); return *this; } F &operator/=(const F &g) { ll n = (*this).size(); *this = convolution(*this, g.inv(n)); (*this).resize(n); return *this; } // // naive // F &operator*=(const F &g) { // ll n = (*this).size(), m = g.size(); // for (ll i = n-1; i >= 0; --i) { // (*this)[i] *= g[0]; // Rep(j, 1, min(i+1, m)) (*this)[i] += (*this)[i-j] * g[j]; // } // return *this; // } // F &operator/=(const F &g) { // assert(g[0] != T(0)); // T ig0 = g[0].inv(); // ll n = (*this).size(), m = g.size(); // rep(i, n) { // Rep(j, 1, min(i+1, m)) (*this)[i] -= (*this)[i-j] * g[j]; // (*this)[i] *= ig0; // } // return *this; // } // sparse F &operator*=(vector> g) { ll n = (*this).size(); auto [d, c] = g.front(); if (d == 0) g.erase(g.begin()); else c = 0; for (ll i = n-1; i >= 0; --i) { (*this)[i] *= c; for (auto &[j, b] : g) { if (j > i) break; (*this)[i] += (*this)[i-j] * b; } } return *this; } F &operator/=(vector> g) { ll n = (*this).size(); auto [d, c] = g.front(); assert(d == 0 && c != T(0)); T ic = c.inv(); g.erase(g.begin()); rep(i, n) { for (auto &[j, b] : g) { if (j > i) break; (*this)[i] -= (*this)[i-j] * b; } (*this)[i] *= ic; } return *this; } // multiply and divide (1 + cz^d) void multiply(const ll d, const T c) { ll n = (*this).size(); if (c == T(1)) for (ll i = n-d-1; i >= 0; --i) (*this)[i+d] += (*this)[i]; else if (c == T(-1)) for (ll i = n-d-1; i >= 0; --i) (*this)[i+d] -= (*this)[i]; else for (ll i = n-d-1; i >= 0; --i) (*this)[i+d] += (*this)[i] * c; } void divide(const ll d, const T c) { ll n = (*this).size(); if (c == T(1)) rep(i, n-d) (*this)[i+d] -= (*this)[i]; else if (c == T(-1)) rep(i, n-d) (*this)[i+d] += (*this)[i]; else rep(i, n-d) (*this)[i+d] -= (*this)[i] * c; } T eval(const T &a) const { T x(1), res(0); for (auto e : *this) res += e * x, x *= a; return res; } F operator*(const T &g) const { return F(*this) *= g; } F operator/(const T &g) const { return F(*this) /= g; } F operator+(const F &g) const { return F(*this) += g; } F operator-(const F &g) const { return F(*this) -= g; } F operator<<(const ll d) const { return F(*this) <<= d; } F operator>>(const ll d) const { return F(*this) >>= d; } F operator*(const F &g) const { return F(*this) *= g; } F operator/(const F &g) const { return F(*this) /= g; } F operator*(vector> g) const { return F(*this) *= g; } F operator/(vector> g) const { return F(*this) /= g; } }; using mint = modint998244353; using fps = FormalPowerSeries; using sfps = vector>; int main() { ll n, x; cin >> n >> x; fps f(101000); rep(i,n) { ll a; cin >> a; f[a]++; } f *= f; cout << f[x].val() << '\n'; }