package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
	var n int
	var a string
	reader := bufio.NewReader(os.Stdin)
	fmt.Fscan(reader, &n, &a)

	const mod = 998244353

	canZero := make([]bool, n)
	canOne := make([]bool, n)

	existsZero := false
	for i := 0; i < n; i++ {
		if a[i] == '0' {
			existsZero = true
		}
		canZero[i] = existsZero
	}

	existsOne := false
	for i := n - 1; i >= 0; i-- {
		if a[i] == '1' {
			existsOne = true
		}
		canOne[i] = existsOne
	}

	dp := make([][2]int, n+1)
	
	if canZero[0] {
		dp[1][0] = 1
	}
	if canOne[0] {
		dp[1][1] = 1
	}

	for i := 2; i <= n; i++ {
		idx := i - 1
		sumPrev := (dp[i-1][0] + dp[i-1][1]) % mod
		
		if canZero[idx] {
			dp[i][0] = sumPrev
		}
		if canOne[idx] {
			dp[i][1] = sumPrev
		}
	}

	fmt.Println((dp[n][0] + dp[n][1]) % mod)
}