#include <stdio.h>
#define MOD 998244353

int a;
long long int check[1510][3010][4];
char x[1510];
long long int func(int s, int t, int type)
{
	if(s>a)
	{
		if(t<=0&& (-t)%2==0) return 1;
		else return 0;
	}
	if(check[s][t+1500][type]!=-1) return check[s][t+1500][type];
	
	long long int ans;
	if(type==0) // last = 0
	{
		long long int s1 = func(s+1,t+1,0);
		long long int s2 = func(s+1,t,1);
		if(x[s]=='0') s2 = 0;
		if(x[s]=='1') s1 = 0;
		ans = (s1+s2)%MOD;
	}
	if(type==1) // last = 01
	{
		long long int s1 = func(s+1,t-1,2);
		long long int s2 = func(s+1,t,1);
		if(x[s]=='0') s2 = 0;
		if(x[s]=='1') s1 = 0;
		ans = (s1+s2)%MOD;
	}
	if(type==2) // last = 010
	{
		long long int s1 = func(s+1,t+1,0);
		long long int s2 = func(s+1,t,1);
		if(x[s]=='0') s2 = 0;
		if(x[s]=='1') s1 = 0;
		ans = (s1+s2)%MOD;
	}
	return check[s][t+1500][type] = ans;
}

int main()
{
	scanf("%d",&a);
	for(int i=0;i<=1500;i++) for(int j=0;j<=3000;j++) for(int k=0;k<=2;k++) check[i][j][k] = -1;
	scanf("%s",x+1);
	
	long long int ans = 0;
	for(int i=1;i<=a;i++)
	{
		if(x[i]=='1') continue;
		ans += func(i+1,1,0), ans %= MOD;
		if(x[i]=='0') goto u;
	}
	ans++, ans %= MOD;
	u:;
	printf("%lld",ans);
}