#include <bits/stdc++.h>

using namespace std;

using ll = long long;

constexpr char newl = '\n';
constexpr int geta = 2;

// https://noshi91.hatenablog.com/entry/2019/03/31/174006
template <std::uint_fast64_t Modulus>
struct ModInt {
    using u64 = std::uint_fast64_t;

    static constexpr u64 MOD = Modulus;

    u64 val;

    constexpr ModInt(const u64 x = 0) noexcept : val(x % MOD) {}

    constexpr ModInt operator+() const noexcept { return ModInt(*this); }
    constexpr ModInt operator-() const noexcept {
        ModInt res(*this);
        if (res.val != 0) res.val = MOD - res.val;
        return res;
    }

    constexpr bool operator==(const ModInt& rhs) const noexcept { return val == rhs.val; }
    constexpr bool operator!=(const ModInt& rhs) const noexcept { return val != rhs.val; }

    // prefix increment/decrement
    constexpr ModInt& operator++() noexcept { return *this += ModInt(1); }
    constexpr ModInt& operator--() noexcept { return *this -= ModInt(1); }

    // postfix increment/decrement
    constexpr ModInt operator++(int) noexcept {
        ModInt tmp(*this);
        ++*this;
        return tmp;
    }
    constexpr ModInt operator--(int) noexcept {
        ModInt tmp(*this);
        --*this;
        return tmp;
    }

    constexpr ModInt operator+(const ModInt& rhs) const noexcept {
        return ModInt(*this) += rhs;
    }
    constexpr ModInt operator-(const ModInt& rhs) const noexcept {
        return ModInt(*this) -= rhs;
    }
    constexpr ModInt operator*(const ModInt& rhs) const noexcept {
        return ModInt(*this) *= rhs;
    }
    constexpr ModInt operator/(const ModInt& rhs) const noexcept {
        return ModInt(*this) /= rhs;
    }

    constexpr ModInt& operator+=(const ModInt& rhs) noexcept {
        val += rhs.val;
        if (val >= MOD) val -= MOD;
        return *this;
    }
    constexpr ModInt& operator-=(const ModInt& rhs) noexcept {
        if (val < rhs.val) val += MOD;
        val -= rhs.val;
        return *this;
    }
    constexpr ModInt& operator*=(const ModInt& rhs) noexcept {
        val = val * rhs.val % MOD;
        return *this;
    }

    // prime Modulus only
    constexpr ModInt& operator/=(const ModInt& rhs) noexcept {
        return *this *= rhs.inv();
    }

    // prime Modulus only
    constexpr ModInt inv() const noexcept {
        return pow(*this, MOD - 2);
    }
};

template<std::uint_fast64_t Modulus>
constexpr ModInt<Modulus> pow(ModInt<Modulus> x, std::uint_fast64_t n) {
    ModInt<Modulus> res(1);
    while (n) {
        if (n & 1) res *= x;
        x *= x;
        n >>= 1;
    }
    return res;
}

template<std::uint_fast64_t Modulus>
istream& operator>>(istream& is, ModInt<Modulus>& x) {
    std::uint_fast64_t val;
    is >> val;
    x = ModInt<Modulus>(val);
    return is;
}

template<std::uint_fast64_t Modulus>
ostream& operator<<(ostream& os, const ModInt<Modulus>& x) {
    return os << x.val;
}

using mint = ModInt<998244353>;

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);

    int n;
    cin >> n;

    vector<mint> dp(6, 0), cnt(6, 0);
    cnt[1 + geta] = 1;
    mint ans = 0;
    for (int i = 0; i < n; i++) {
        int a;
        cin >> a;

        vector<mint> ndp(6, 0), ncnt(6, 0);
        for (int j = -2; j < 4; j++) {
            int nj = j * a;
            if (abs(nj) > 2) nj = 3;
            ncnt[nj + geta] += cnt[j + geta];
            ndp[nj + geta] += dp[j + geta];
        }

        cnt = move(ncnt);
        dp = move(ndp);

        mint cnt1 = 0, dp1 = 0;
        for (int j = -2; j < 4; j++) {
            cnt1 += cnt[j + geta];
            dp1 += dp[j + geta] + (j == -2 ? cnt[j + geta] : mint(0));
        }
        cnt[1 + geta] += cnt1;
        dp[1 + geta] += dp1;
        ans = dp1;

        /*
        for (int j = -2; j < 4; j++) {
            cerr << j << ": " << cnt[j + geta] << " " << dp[j + geta] << newl;
        }*/
    }
    cout << ans / pow(mint(2), n - 1) << newl;
    
    return 0;
}