// #pragma GCC target("avx2")
// #pragma GCC optimize("O3")
// #pragma GCC optimize("unroll-loops")
#include <algorithm>
#include <bitset>
#include <cassert>
#include <climits>
#include <cmath>
#include <complex>
#include <deque>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <vector>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define TEST cerr << "TEST" << endl
#define AMARI 998244353
// #define AMARI 1000000007
#define TIME_LIMIT 1980000
#define el '\n'
#define El '\n'

#define MULTI_TEST_CASE false
void solve(void) {
    int n;
    string s;
    cin >> n >> s;
    vector<ll> dp0(n + 1,0),dp1(n + 1,0);
    dp0[0] = 1;
    for(int i = 0; i < n; i++){
        if(s[i] == '0'){
            dp1[i + 1] = dp1[i];
            dp0[i + 1] = dp0[i] + dp1[i];
            dp0[i + 1] %= AMARI;
        }
        if(s[i] == '1'){
            dp0[i + 1] = dp0[i] + dp1[i];
            dp1[i + 1] = dp1[i] + dp0[i];
            dp0[i + 1] %= AMARI;
            dp1[i + 1] %= AMARI;
        }
    }
    cout << dp1.back() << el;
    return;
}

void calc(void) {
    return;
}

signed main(void) {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    calc();
    int t = 1;
    if(MULTI_TEST_CASE) cin >> t;
    while(t--) {
        solve();
    }
    return 0;
}