#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MOD = 998244353;
ll dp[200010][2][3][3];
int main()
{
  int N;
  cin >> N;
  vector<int>A(N);
  for(int i = 0; i < N; i++) cin >> A[i];
  dp[0][0][0][0] = 1;
  for(int i = 0; i < N; i++){
    int neg = A[i] < 0 ? 1 : 0;
    int two = A[i] == 0 ? 2 : (abs(A[i]) == 2 ? 1 : 0);
    for(int j = 0; j < 2; j++){
      for(int k = 0; k < 3; k++){
        if(i == 0) (dp[i + 1][j][k][0] += dp[i][j][k][0]) %= MOD;
        else (dp[i + 1][j][k][0] += 2 * dp[i][j][k][0]) %= MOD;

        (dp[i + 1][(j + neg) % 2][min(2, k+two)][1] += dp[i][j][k][0] + dp[i][j][k][1]) %= MOD;
        (dp[i + 1][(j + neg) % 2][min(2, k+two)][2] += dp[i][j][k][0] + dp[i][j][k][1]) %= MOD;

        if(i == N - 1) (dp[i + 1][j][k][2] += dp[i][j][k][2]) %= MOD;
        else (dp[i + 1][j][k][2] += 2 * dp[i][j][k][2]) %= MOD;
      }
    }
  }
  ll ans = dp[N][1][1][2];
  for(int i = 0; i < N - 1; i++)(ans *= 499122177) %= MOD;
  cout << ans << endl;

  return 0;
}