#pragma GCC optimize("Ofast", "unroll-loops")
#pragma GCC target("avx2")

#include <bits/stdc++.h>

using namespace std;

#define ll long long

constexpr ll mod = 998244353LL;

ll modpow(ll a, int b){
    if (b == 0) return 1LL;
    ll tmp = modpow(a, b / 2);
    tmp = tmp * tmp % mod;
    if (b % 2 == 0) return tmp;
    return tmp * a % mod;
}

ll inverse(ll a){ return modpow(a, mod - 2); }

int N;
vector<int> A;

void input(void){
    cin >> N;
    A.resize(N);
    for (int& ai : A)
        cin >> ai;
}

ll solve(void){
    constexpr int offset = 2;
    static ll dp[2][5];
    dp[0][A[0] + offset] = 1LL;
    ll ret = dp[0][0];
    for (int i = 1; i < N; ++i){
        int a = A[i];
        for (int j = 0; j < 5; ++j)
            dp[i & 1][j] = 0;
        dp[i & 1][a + offset] = modpow(2, i - 1);
        for (int prv = -2; prv <= 2; ++prv){
            int nxt = prv * a;
            if (abs(nxt) <= 2){
                dp[i & 1][nxt + offset] += dp[(i - 1) & 1][prv + offset];
                dp[i & 1][nxt + offset] %= mod;
            }
        }
        if (i < N - 1)
            ret = ret * 2 % mod;
        ret += dp[i & 1][0];
    }
    ll tmp = modpow(2, N - 1);
    return ret * inverse(tmp) % mod;
}

int main(void){
    input();
    cout << solve() << endl;
    return 0;
}