#include<stdio.h>
#include<string.h>
#include<stdlib.h>
#include <map>
#include <vector>
#include <queue>
#include <deque>
#include <set>
#include <stack>
#include <algorithm>
#include <array>
#include <unordered_set>
#include <unordered_map>
#include <string>
using namespace std;

bool rcmp(int a, int b) { return a>b; }
typedef long long LL;
class mypcmp {
public:
    bool operator()(const int& a, const int& b) {
        return a<b;
    }
};


#define MOD 998244353
char ib[4004];
int dp[4004];
int bb[4004];
int main() {
    int n, i, ni, c;
    LL b, s1, r, t;
    scanf("%d %s", &n, ib);
    bb[0]=1; for (i=1; i<=n; i++) bb[i]=(bb[i-1]*2)%MOD;
    r=0;
    for (b=0; b<n; b++) {
        dp[n]=0;
        s1=0;
        for (i=n-1; i>=0; i--) {
            if (ib[i]=='1') {
                ni=i+b+1;
                if (ni<=n) {
                    s1-=dp[ni];
                    c=n-ni-1; if (c<0) c=0;
                    s1+=bb[c];
                    s1%=MOD; if (s1<0) s1+=MOD;
                }
            }
            dp[i]=s1;
            // printf("dp %d,%d: %lld\n", b, i, s1);
            s1+=dp[i]; s1%=MOD;
        }
        t=dp[0]; t*=bb[b]; t%=MOD;
        r+=t; r%=MOD;
    }
    printf("%lld\n", r);
    return 0;
}