#include using namespace std; using ll = long long; using ld = long double; using pll = pair; using tlll = tuple; constexpr ll INF = 1LL << 60; template bool chmin(T& a, T b) {if (a > b) {a = b; return true;} return false;} template 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 void unique(vector &V) {V.erase(unique(V.begin(), V.end()), V.end());} template void sortunique(vector &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 void printvec(const vector &V) {int _n = V.size(); for (int i = 0; i < _n; i++) cout << V[i] << (i == _n - 1 ? "" : " ");cout << '\n';} template void printvect(const vector &V) {for (auto v : V) cout << v << '\n';} template void printvec2(const vector> &V) {for (auto &v : V) printvec(v);} //* #include 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>> &dp, ll i) -> vector>> { 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.operator[](i) == '?' || S.operator[](i) == '0') { ll nj = j + 1; ll nl = (l + 1) % 2; if (0 <= nj && nj < 6 * N) ndp.operator[](nj).operator[](0).operator[](nl) += dp.operator[](j).operator[](k).operator[](l); } if (S.operator[](i) == '?' || S.operator[](i) == '1') { ll nj = (k == 0 ? j - 2 : j); if (0 <= nj && nj < 6 * N) ndp.operator[](nj).operator[](1).operator[](l) += dp.operator[](j).operator[](k).operator[](l); } } } } return ndp; }; vector dp(6 * N, vector(2, vector(2, mint(0)))); dp.operator[](3 * N).operator[](1).operator[](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.operator[](j).operator[](k).operator[](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; }