#pragma region template
#include <bits/stdc++.h>

using namespace std;

// clang-format off
#include <atcoder/modint.hpp>

using namespace atcoder;
using mint = static_modint<998244353>;
using vm = vector<mint>;
using vvm = vector<vm>;
ostream& operator<<(ostream& os, const mint& v){ os << v.val(); return os; }

using ll = long long; using vl = vector<ll>; using vvl = vector<vl>;
using ld = long double; using vld = vector<ld>; using vvld = vector<vld>;
using pll = pair<ll, ll>; using vpll = vector<pll>; using vvpll = vector<vpll>;
template <class T> using V = vector<T>; template <class T> using VV = vector<V<T>>;
template <class T> using VVV = vector<VV<T>>;
using vb = vector<bool>;
using vs = vector<string>;
using mll = map<ll, ll>;
using msl = map<string, ll>;
template<class T> using     heap = priority_queue<T>;
template<class T> using min_heap = priority_queue<T, vector<T>, greater<T>>;
constexpr ll inf = 3001001000100100100LL;
constexpr int inf_int = 1000000009;
#define endl '\n'

#define  _overload(_1, _2, _3, name, ...) name
#define   rep(...) _overload(__VA_ARGS__,   _rep,   _rep2,)(__VA_ARGS__)
#define  repc(...) _overload(__VA_ARGS__,  _repc,  _repc2,)(__VA_ARGS__)
#define  repr(...) _overload(__VA_ARGS__,  _repr,  _repr2,)(__VA_ARGS__)
#define reprc(...) _overload(__VA_ARGS__, _reprc, _reprc2,)(__VA_ARGS__)
#define   _rep(i,k,n) for(ll i=(k)  , i##_xxxx=(n); i < i##_xxxx; ++i)
#define  _repc(i,k,n) for(ll i=(k)  , i##_xxxx=(n); i <=i##_xxxx; ++i)
#define  _repr(i,k,n) for(ll i=(n)-1, i##_xxxx=(k); i >=i##_xxxx; --i)
#define _reprc(i,k,n) for(ll i=(n)  , i##_xxxx=(k); i >=i##_xxxx; --i)
#define   _rep2(i,n)   _rep(i,0,n)
#define  _repc2(i,n)  _repc(i,1,n)
#define  _repr2(i,n)  _repr(i,0,n)
#define _reprc2(i,n) _reprc(i,1,n)

#define rall(o) rbegin(o), rend(o)
#define  all(o)  begin(o),  end(o)
template <class C> ll sz(const C& c) { return static_cast<ll>(c.size()); }
template <class T> bool chmax(T& m, const T& v){ if (m < v){ m = v; return true; } return false; }
template <class T> bool chmin(T& m, const T& v){ if (v < m){ m = v; return true; } return false; }
template <class T> T udiv(const T& a, const T& b){ return (a + b - 1) / b; }
template <class T> T rdiv(const T& a, const T& b){ return (a + b / 2) / b; }
template <class T, class S>             string join(const T& v, const S& sep                  ){ stringstream ss; bool f = false; for (const auto& e : v){ if (f) ss << sep; f = true; ss << e;} return ss.str(); }
template <class T, class S, class... U> string join(const T& v, const S& sep, const U& ...args){ stringstream ss; bool f = false; for (const auto& c : v){ if (f) ss << sep; f = true; ss << join(c, args...); } return ss.str(); }
template <class T>            ostream& operator<<(ostream& os, const vector<T>&            seq){ os << '[' << join(seq, ",") << ']'; return os; } template <class T>            ostream& operator<<(ostream& os, const vector<vector<T>>&    seq){ os << '[' << join(seq, ",\n ") << ']'; return os; }
template <class T>            ostream& operator<<(ostream& os, const deque<T>&             seq){ os << '[' << join(seq, ",") << ']'; return os; }
template <class T>            ostream& operator<<(ostream& os, const set<T>&               seq){ os << '{' << join(seq, ",") << '}'; return os; }
template <class T , class TH> ostream& operator<<(ostream& os, const unordered_set<T, TH>& seq){ os << '{' << join(seq, ",") << '}'; return os; }
template <class TK, class TV> ostream& operator<<(ostream& os, const map<TK, TV>&          seq){ os << '{'; bool f = false; for (const auto& e : seq){ if (f) os << ','; f = true; os << e.first << ":" << e.second; } os << '}'; return os; }
template <class T1, class T2> ostream& operator<<(ostream& os, const pair<T1, T2>&          pa){ os << '(' << pa.first << ',' << pa.second << ')'; return os; }

#if LOCAL
#define debug(...) _debug(__VA_ARGS__, __LINE__)
#else
#define debug(...)
#endif
void print() { std::cout << '\n'; }
template <class S>             void  print(const S& a){ std::cout << a << '\n'; }
template <class S>             void _debug(const S& a){ std::cerr << "(L:" << std::setw(3) << a << ")\n"; }
template <class S, class... T> void  print(const S& a, const T&... args){ std::cout << a << ' ';  print(args...); }
template <class S, class... T> void _debug(const S& a, const T&... args){ std::cerr << a << ' '; _debug(args...); }

struct setup_main { setup_main() { std::cin.tie(nullptr); std::ios::sync_with_stdio(false); std::cout << fixed << setprecision(15); } } setup_main_;
// clang-format on
#pragma endregion

ll cnt(ll n) {
    // if (n == 0) return 0;
    ll ret = 0;
    while (n % 2 == 0) {
        ret++;
        n /= 2;
    }
    return ret;
}

void solve(ll N, vector<ll>& B) {
    vl c(N, 0);
    rep(i, N - 1) {
        // debug(N, i, N - 1 - i, i + 1);
        c[i + 1] = c[i] + cnt(N - 1 - i) - cnt(i + 1);
    }
    vl f(N);
    rep(i, N) f[i] = (c[i] == 0 ? 1 : 0);

    ll free = 0, k = 0, r = 0;
    rep(i, N) {
        if (B[i] == 1 and f[i] == 1) r++;
        if (B[i] == -1 and f[i] == 0) free++;
        if (B[i] == -1 and f[i] == 1) k++;
    }
    r %= 2;

    if (k == 0) {
        print(r == 1 ? mint(2).pow(free) : 0);
        return;
    }
    print(mint(2).pow(free + k - 1));

    // mint S = 0, C = 1;
    // rep(i, k + 1) {
    //     if (i % 2 != r) S += C;
    //     // C_i → C_i+1
    //     C = C * (k - i) / (i + 1);
    // }

    // print(S * mint(2).pow(free));
}


int main() {
    int N;
    cin >> N;
    vector<ll> B(N);
    rep(i, N) {
        cin >> B[i];
    }

    solve(N, B);
}