#include <bits/stdc++.h>
#define fastio ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;

typedef long long LL;
LL MOD = 998244353;

int main() {
    int N;
    cin >> N;
    vector<char> S(N);
    for (int i = 0; i < N; i++) cin >> S[N- 1 - i];
    if (S[0] == '1' || S[1] == '1' || S[N - 1] == '1') {
        cout << 0 << endl;
        return 0;
    }

    // m[A][B][C]: A = (# of 0) - 3*(# of 1) + N / 4, B = A - min preA, C = 0 or 1
    vector<vector<vector<int>>> m(N+1, vector<vector<int>>(N/2+1, vector<int>(2, 0)));
    m[2+N/4][2][0] = 1;
    for (int pos = 2; pos <N;pos++) {
        vector<vector<vector<int>>> mp(N+1, vector<vector<int>>(N/2+1, vector<int>(2, 0)));
        for (int a = 0; a <= N; a++) {
            for (int b = 0; b <= N/2; b++) {
                for (int c = 0; c < 2; c++) {
                    int t = m[a][b][c];
                    if (S[pos] != '1' && a+1 <= N && b+1 <= N/2) {
                        mp[a+1][b+1][0] += t;
                        mp[a+1][b+1][0] %= MOD; 
                    }
                    if (S[pos] != '0' && c == 0 && b > 1 && a-3 >= 0) {
                        mp[a-3][max(b-3, 0)][1] += t;
                        mp[a-3][max(b-3, 0)][1] %= MOD;
                    }
                }
            }
        }
        swap(m, mp);
    }
    LL ans = 0;
    for (int b = 0; b <= N/4; b++) {
        ans += m[N/4][b][0];
        ans %= MOD;
    }
    cout << ans << endl;
}