#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
using namespace std;
using i32 = int32_t;
using u32 = uint32_t;
using i64 = int64_t;
using u64 = uint64_t;
#define rep(i,n) for(int i=0; i<(n); i++)


int main(){
    int N; cin >> N;
    vector<int> Fdivcnt2(N + 1, 0);
    for (int i = 2; i <= N; i++) Fdivcnt2[i] = (i / 2) + Fdivcnt2[i / 2];
    
    int open_sum = 0;
    int prob0 = 0;
    int prob1 = 0;

    rep(i, N) {
        int b; cin >> b;
        if (Fdivcnt2[i] + Fdivcnt2[N - 1 - i] == Fdivcnt2[N - 1]) {
            if (b == 0) open_sum ^= 0;
            if (b == 1) open_sum ^= 1;
            if (b == -1) prob1 ++;
        }
        else{
            if (b == 0) open_sum ^= 0;
            if (b == 1) open_sum ^= 0;
            if (b == -1) prob0 ++;
        }
    }

    i64 ans[2] = {};
    ans[open_sum] = 1;
    rep(i, prob0) {
        rep(t, 2) ans[t] = ans[t] * 2 % 998244353;
    }
    rep(i, prob1) {
        ans[0] = ans[1] = (ans[0] + ans[1]) % 998244353;
    }

    cout << ans[1] << endl;
    return 0;
}




struct ios_do_not_sync {
    ios_do_not_sync() {
        ios::sync_with_stdio(false);
        cin.tie(nullptr);
    }
} ios_do_not_sync_instance;