#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = long double;
using pll = pair<ll, ll>;
using tlll = tuple<ll, ll, ll>;
constexpr ll INF = 1LL << 60;
template<class T> bool chmin(T& a, T b) {if (a > b) {a = b; return true;} return false;}
template<class T> bool chmax(T& a, T b) {if (a < b) {a = b; return true;} return false;}
ll safemod(ll A, ll M) {ll res = A % M; if (res < 0) res += M; return res;}
ll divfloor(ll A, ll B) {if (B < 0) {return divfloor(-A, -B);} return (A - safemod(A, B)) / B;}
ll divceil(ll A, ll B) {if (B < 0) {return divceil(-A, -B);} return divfloor(A + B - 1, B);}
ll pow_ll(ll A, ll B) {if (A == 0 || A == 1) {return A;} if (A == -1) {return B & 1 ? -1 : 1;} ll res = 1; for (int i = 0; i < B; i++) {res *= A;} return res;}
ll logfloor(ll A, ll B) {assert(A >= 2); ll res = 0; for (ll tmp = 1; tmp <= B / A; tmp *= A) {res++;} return res;}
ll logceil(ll A, ll B) {assert(A >= 2); ll res = 0; for (ll tmp = 1; tmp < B; tmp *= A) {res++;} return res;}
ll arisum_ll(ll a, ll d, ll n) { return n * a + (n & 1 ? ((n - 1) >> 1) * n : (n >> 1) * (n - 1)) * d; }
ll arisum2_ll(ll a, ll l, ll n) { return n & 1 ? ((a + l) >> 1) * n : (n >> 1) * (a + l); }
ll arisum3_ll(ll a, ll l, ll d) { assert((l - a) % d == 0); return arisum2_ll(a, l, (l - a) / d + 1); }
template<class T> void unique(vector<T> &V) {V.erase(unique(V.begin(), V.end()), V.end());}
template<class T> void sortunique(vector<T> &V) {sort(V.begin(), V.end()); V.erase(unique(V.begin(), V.end()), V.end());}
#define FINALANS(A) do {cout << (A) << '\n'; exit(0);} while (false)
template<class T> void printvec(const vector<T> &V) {int _n = V.size(); for (int i = 0; i < _n; i++) cout << V[i] << (i == _n - 1 ? "" : " ");cout << '\n';}
template<class T> void printvect(const vector<T> &V) {for (auto v : V) cout << v << '\n';}
template<class T> void printvec2(const vector<vector<T>> &V) {for (auto &v : V) printvec(v);}
//*
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
//using mint = modint1000000007;
//using mint = modint;
//*/

int main()
{
  ll N;
  cin >> N;
  string S;
  cin >> S;

  auto nxt = [&](vector<vector<vector<mint>>> &dp, ll i) -> vector<vector<vector<mint>>>
  {
    vector ndp(6 * N, vector(2, vector(2, mint(0))));
    for (ll j = 0; j < 6 * N; j++)
    {
      for (ll k = 0; k < 2; k++)
      {
        for (ll l = 0; l < 2; l++)
        {
          if (S.at(i) == '?' || S.at(i) == '0')
          {
            ll nj = j + 1;
            ll nl = (l + 1) % 2;
            if (0 <= nj && nj < 6 * N)
              ndp.at(nj).at(0).at(nl) += dp.at(j).at(k).at(l);
          }
          if (S.at(i) == '?' || S.at(i) == '1')
          {
            ll nj = (k == 0 ? j - 2 : j);
            if (0 <= nj && nj < 6 * N)
              ndp.at(nj).at(1).at(l) += dp.at(j).at(k).at(l);
          }
        }
      }
    }
    return ndp;
  };

  vector dp(6 * N, vector(2, vector(2, mint(0))));
  dp.at(3 * N).at(1).at(0) = 1;
  for (ll i = 0; i < N; i++)
  {
    dp = nxt(dp, i);
  }
  mint ans = 0;
  for (ll j = 0; j <= 3 * N; j++)
  {
    for (ll k = 0; k < 2; k++)
    {
      mint tmp = dp.at(j).at(k).at(0);
      ll j2 = (k == 1 ? j + 2 : j);
      if (j2 <= 3 * N)
      {
        //if (tmp != 0) cerr << j2 - 3 * N << endl;
        ans += tmp;
      }
    }
  }
  if (count(S.begin(), S.end(), '0') == 0)
    ans++;
  cout << ans.val() << endl;
}