#include using namespace std; template struct prime_modint { using mint = prime_modint; unsigned int v; prime_modint() : v(0) {} prime_modint(unsigned int a) { a %= MOD; v = a; } prime_modint(unsigned long long a) { a %= MOD; v = a; } prime_modint(int a) { a %= (int)(MOD); if(a < 0)a += MOD; v = a; } prime_modint(long long a) { a %= (int)(MOD); if(a < 0)a += MOD; v = a; } static constexpr int mod() { return MOD; } mint& operator++() {v++; if(v == MOD)v = 0; return *this;} mint& operator--() {if(v == 0)v = MOD; v--; return *this;} mint operator++(int) { mint result = *this; ++*this; return result; } mint operator--(int) { mint result = *this; --*this; return result; } mint& operator+=(const mint& rhs) { v += rhs.v; if(v >= MOD) v -= MOD; return *this; } mint& operator-=(const mint& rhs) { if(v < rhs.v) v += MOD; v -= rhs.v; return *this; } mint& operator*=(const mint& rhs) { v = (unsigned int)((unsigned long long)(v) * rhs.v % MOD); return *this; } mint& operator/=(const mint& rhs) { return *this = *this * rhs.inv(); } mint operator+() const { return *this; } mint operator-() const { return mint() - *this; } mint pow(long long n) const { assert(0 <= n); mint r = 1, x = *this; while (n) { if (n & 1) r *= x; x *= x; n >>= 1; } return r; } mint inv() const { assert(v); return pow(MOD - 2); } friend mint operator+(const mint& lhs, const mint& rhs) { return mint(lhs) += rhs; } friend mint operator-(const mint& lhs, const mint& rhs) { return mint(lhs) -= rhs; } friend mint operator*(const mint& lhs, const mint& rhs) { return mint(lhs) *= rhs; } friend mint operator/(const mint& lhs, const mint& rhs) { return mint(lhs) /= rhs; } friend bool operator==(const mint& lhs, const mint& rhs) { return (lhs.v == rhs.v); } friend bool operator!=(const mint& lhs, const mint& rhs) { return (lhs.v != rhs.v); } friend std::ostream& operator << (std::ostream &os, const mint& rhs) noexcept { return os << rhs.v; } }; //using mint = prime_modint<1000000007>; using mint = prime_modint<998244353>; int main(){ ios::sync_with_stdio(false); cin.tie(0); int n, prv = -1; string s; cin >> n >> s; mint ans = 1; for(int i = 0; i < n; i++){ if(s[i] == '1'){ if(prv != -1) ans *= i - prv + 1; prv = i; } } cout << (prv == -1 ? 0 : ans) << '\n'; }