#include<bits/stdc++.h>
using namespace std;


int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N;
    cin >> N;
    string A;
    cin >> A;

    const int MOD = 998244353;

    vector<bool> ok1(N, false), ok2(N, false);
    
    bool ans0 = false;
    for (int i = 0; i < N; ++i) {
        if (A[i] == '0') ans0 = true;
        ok1[i] = ans0;
    }

    bool ans1 = false;
    for (int i = N - 1; i >= 0; --i) {
        if (A[i] == '1') ans1 = true;
        ok2[i] = ans1;
    }

    vector<long long> dp(2, 0);
    if (ok1[0]) dp[0] = 1;
    if (ok2[0]) dp[1] = 1;

    for (int i = 0; i < N - 1; ++i) {
        vector<long long> next_dp(2, 0);
        
        for (int curr = 0; curr <= 1; ++curr) {
            if (dp[curr] == 0) continue;

            for (int nxt = 0; nxt <= 1; ++nxt) {
                if (nxt == 0 && !ok1[i + 1]) continue;
                if (nxt == 1 && !ok2[i + 1]) continue;

                if (curr == 1 && nxt == 0) {
                    if (!(A[i] == '1' && A[i + 1] == '0')) {
                        continue;
                    }
                }

                next_dp[nxt] = (next_dp[nxt] + dp[curr]) % MOD;
            }
        }
        dp = next_dp;
    }

    long long ans = (dp[0] + dp[1]) % MOD;
    cout << ans << endl;

    return 0;
}