#include <bits/stdc++.h>

using namespace std;

using pii = pair<int, int>;
using ll = long long;
const int N = 2000010, MOD = 998244353, INF = 0x3f3f3f3f;
int n, m, w[N];


char s[N];
ll f[N][3];
void solve() {
    scanf("%d%s", &n, s + 1);
    if (s[1] == '0') f[1][0] = f[1][2] = 1;
    else f[1][1] = 1;
    for (int i = 2; i < n + 1; i++) {
        if (s[i] == '0') {
            f[i][0] = (f[i - 1][0] + f[i - 1][1]) % MOD;
            f[i][2] = (f[i - 1][0] + f[i - 1][1] + f[i - 1][2]) % MOD;
        } else {
            f[i][0] = f[i - 1][0] % MOD;
            f[i][1] = (f[i - 1][0] + f[i - 1][1] + f[i - 1][2]) % MOD;
        }
    }
    printf("%lld\n", (f[n][0] + f[n][1]) % MOD);
}

int main() {
    int T = 1;
    // cin >> T;
    while (T--) solve();
    return 0;
}