#include #include #include #include #include #include #include #include #include #include #include #include #include #define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl; #define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl; template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } using namespace std; typedef long long ll; template vector> vec2d(int n, int m, T v){ return vector>(n, vector(m, v)); } template vector>> vec3d(int n, int m, int k, T v){ return vector>>(n, vector>(m, vector(k, v))); } template void print_vector(vector v, char delimiter=' '){ if(v.empty()) { cout << endl; return; } for(int i = 0; i+1 < v.size(); i++) cout << v[i] << delimiter; cout << v.back() << endl; } const ll MOD = 998244353; class ModInt{ public: ll v; ModInt(ll _v = 0){ if(_v < 0) _v = (_v%MOD)+MOD; if(_v >= MOD) _v %= MOD; v = _v; } ModInt operator+(ll n){ return ModInt((v+n)%MOD); } ModInt operator-(ll n){ return ModInt((v-n+MOD)%MOD); } ModInt operator*(ll n){ if(n >= MOD) n %= MOD; return ModInt((v*n)%MOD); } ModInt operator/(ll n){ return ModInt((ModInt(n).inv()*v).v%MOD); } void operator+=(ll n){ v = (v+n)%MOD; } void operator-=(ll n){ v = (v-n+MOD)%MOD; } void operator*=(ll n){ v = (v*n+MOD)%MOD; } ModInt operator+(ModInt n){ return ModInt((v+n.v)%MOD); } ModInt operator-(ModInt n){ return ModInt((v-n.v+MOD)%MOD); } ModInt operator*(ModInt n){ return ModInt((v*n.v)%MOD); } ModInt operator/(ModInt n){ return ModInt((n.inv()*v).v%MOD); } void operator+=(ModInt n){ v = (v+n.v)%MOD; } void operator-=(ModInt n){ v = (v-n.v+MOD)%MOD; } void operator*=(ModInt n){ v = (v*n.v)%MOD; } void operator=(ModInt n){ v = n.v; } bool operator==(ModInt n){ return v == n.v; } bool operator!=(ModInt n){ return v != n.v; } void operator=(ll n){ v = n%MOD; } ModInt inv(){ if(v == 1) return ModInt(1); else return ModInt(MOD-ModInt(MOD%v).inv().v*(MOD/v)%MOD); } }; ostream& operator<<(ostream& os, const ModInt& m){ os << m.v; return os; } istream & operator >> (istream &in, ModInt &m){ in >> m.v; return in; } using mint = ModInt; /** * thanks to * https://algo-logic.info/is-nck-odd-even/ */ bool is_nCk_odd(int n, int k){ return (n&k)==k; } ModInt pow(ModInt a, ll n) { assert(n >= 0); ModInt ans = 1; ModInt tmp = a; for (int i = 0; i <= 60; i++) { ll m = (ll)1 << i; if (m & n) { ans *= tmp; } tmp *= tmp; } return ans; } #define N_MAX 200002 ModInt inv[N_MAX],fac[N_MAX],finv[N_MAX]; void init(){ fac[0]=1;fac[1]=1; finv[0]=1;finv[1]=1; inv[1]=1; for(int i=2;i> n; vector b(n); for(int i = 0; i < n; i++) cin >> b[i]; int cnt = 0; int x = 0; for(int i = 0; i < n; i++){ if(is_nCk_odd(n, i)){ if(b[i] == 1) cnt++; if(b[i] == -1) x++; } } if(cnt%2 == 0 && x == 0){ cout << 0 << endl; return 0; } if(x == 0){ cout << 1 << endl; return 0; } mint ans = 0; for(int i = 1; i <= x; i += 2) ans += comb(x, i); cout << ans << endl; }