#include<iostream>
#include<cstdio>
#define N 1000000
#define mod 998244353
using namespace std;
int read()
{
	char c=0;
	int sum=0;
	while (c<'0'||c>'9') c=getchar();
	while ('0'<=c&&c<='9') sum=sum*10+c-'0',c=getchar();
	return sum;
}
void Adder(int &x,int d)
{
	x+=d;
	if (x>=mod) x-=mod;
	return;
}
int n,ans,tr[1<<4][2],dp[N+1][1<<4][2];
char c[N+1];
int main()
{
	int d;
	for (int i=0;i<(1<<4);++i)
	{
		d=0;
		if (i&1) d|=2;
		if (i&2) d|=4;
		if (i&4) d|=2;
		tr[i][0]=d,d=0;
		if (i&2) d|=9;
		if (i&8) d|=2;
		tr[i][1]=d;
	}
	n=read(),dp[0][1][0]=1;
	for (int i=1;i<=n;++i)
	{
		cin>>c[i];
		for (int j=0;j<(1<<4);++j)
			for (int opt=0;opt<=1;++opt)
				dp[i][j][opt]=dp[i-1][j][opt];
		for (int op=0;op<=1;++op)
		{
			if (c[i]-'0'==(op^1)) continue;
			for (int j=0;j<(1<<4);++j)
				for (int opt=0;opt<=1;++opt)
					Adder(dp[i][tr[j][op]][opt],dp[i-1][j][opt^1]);
		}
	}
	for (int i=0;i<(1<<4);++i)
		if (!(i&1))
			Adder(ans,dp[n][i][0]);
	Adder(ans,1),printf("%d\n",ans);
	return 0;
}