#include <bits/stdc++.h>
using namespace std;
const long long MOD = 998244353;
int main(){
  int N;
  cin >> N;
  string S;
  cin >> S;
  int r = -1;
  for (int i = 0; i < N; i++){
    if (S[i] == '0'){
      r = i;
    }
  }
  vector<vector<vector<long long>>> dp(N + 1, vector<vector<long long>>(2, vector<long long>(N * 3 + 1, 0)));
  dp[0][1][N] = 1;
  long long ans = 0;
  for (int i = 0; i < N; i++){
    for (int j = 0; j < 2; j++){
      for (int k = 0; k <= N * 3; k++){
        if (dp[i][j][k] > 0){
          if (S[i] != '1'){
            dp[i + 1][0][k - 1] += dp[i][j][k];
            dp[i + 1][0][k - 1] %= MOD;
            if (k - 1 >= N && (k - 1 - N) % 2 == 0 && i >= r){
              ans += dp[i][j][k];
              ans %= MOD;
            }
          }
          if (S[i] != '0'){
            if (j == 0){
              dp[i + 1][1][k + 2] += dp[i][j][k];
              dp[i + 1][1][k + 2] %= MOD;
            } else {
              dp[i + 1][1][k] += dp[i][j][k];
              dp[i + 1][1][k] %= MOD;
            }
          }
        }
      }
    }
  }
  if (r == -1){
    ans++;
    ans %= MOD;
  }
  cout << ans << endl;
}