#include <bits/stdc++.h>
using namespace std;
const long long MOD = 998244353;
int main(){
  int N;
  cin >> N;
  vector<int> c(N);
  for (int i = 0; i < N; i++){
    cin >> c[i];
  }
  vector<long long> POW(N);
  POW[0] = 1;
  for (int i = 0; i < N - 1; i++){
    POW[i + 1] = POW[i] * 2 % MOD;
  }
  if (c[N - 1] <= 0){
    cout << POW[N - 1] << endl;
  } else if (c[0] >= 0){
    cout << POW[N - 1] << endl;
  } else {
    if (find(c.begin(), c.end(), 0) == c.end()){
      cout << POW[N - 1] << endl;
    } else {
      cout << POW[N - 2] * 3 % MOD << endl;
    }
  }
}