#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<(to);x++)
#define FORR(x,arr) for(auto& x:arr)
#define FORR2(x,y,arr) for(auto& [x,y]:arr)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
template<class T> bool chmax(T &a, const T &b) { if(a<b){a=b;return 1;}return 0;}
template<class T> bool chmin(T &a, const T &b) { if(a>b){a=b;return 1;}return 0;}
//-------------------------------------------------------


int N;
string S;

ll from[2020];
ll to[2020];
const ll mo=998244353;

void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>S;
	from[0]=1;
	FOR(i,N) {
		to[0]=from[0];
		FOR(j,N) to[j+1]=(to[j]+from[j+1])%mo;
		ZERO(from);
		if(S[i]=='0') {
			FOR(j,i+1) for(x=1;x<=i+1;x++) {
				if(j>=x) (from[j+1]+=to[j]-(j?to[j-1]:0)+mo)%=mo;
				else (from[x]+=to[j]-(j?to[j-1]:0)+mo)%=mo;
			}
		}
		else {
			FOR(j,i+1) {
				from[j]=(to[j]-(j?to[j-1]:0)+mo)*(i-j+1)%mo;
			}
		}
	}
	ll ret=0;
	FOR(i,N+1) ret+=from[i];
	cout<<ret%mo<<endl;
		
	
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false), cin.tie(0);
	FOR(i,argc-1) s+=argv[i+1],s+='\n'; FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	cout.tie(0); solve(); return 0;
}