package main

import . "fmt"

const Mod = 998244353

func main() {
	var n int
	var s string
	Scan(&n,&s)
	some, none := 0, 0
	if s[0] == '1' {
		some++
	} else {
		none++
	}
	for _, c := range s[1:] {
		if c == '1' {
			some, none = some*2+none, 0
		} else {
			some, none = some, some+none
		}
		some %= Mod
		none %= Mod
	}
	Println(some)
}