use proconio::input;
use proconio::marker::Usize1;
use proconio::marker::Chars;



fn main() {
    input! {
        n: usize,
        s: Chars,
    };

    let mut dp = vec![vec![0i64; 2]; n + 1];
    dp[0][0] = 1;
    let MOD:i64 = 998244353;;
    for i in 1..=n {
        if s[i - 1] == '1' {
            dp[i][1] = dp[i - 1][0] + dp[i - 1][1];
            dp[i][1] += dp[i - 1][1];
            dp[i][1] %= MOD;
        } else {
            dp[i][0] = dp[i - 1][1] + dp[i - 1][0];
            dp[i][1] += dp[i - 1][1];
            dp[i][0] %= MOD;
        }
    }
    println!("{}", dp[n][1]);


}