#include<bits/stdc++.h>
using namespace std;
const int MAXN=1e6+5;
double f;
string a;
double sum[MAXN];
double minx=1e7;
int ans;
struct lst{
    int num;
    int len;
    double xx;
}e[MAXN];
bool cmp(lst a,lst b){
    return a.xx<b.xx;
}
int main(){
    freopen("changgao_real.in","r",stdin);
    freopen("changgao_real.out","w",stdout);
    cin>>f>>a;
    int n=a.length();
    for(int i=1;i<=n;i++){
        if(a[i-1]=='1')sum[i]=sum[i-1]+1;
        else sum[i]=sum[i-1];
    }
    for(int i=1;i<=n;i++){
        double cnt=f*(double)(i);
        int k1=cnt;
        int k2=cnt+1;
        if(abs(f-double(double(k1)/double(i)))<=abs(f-double(double(k2)/double(i)))){
            e[i].len=i;
            e[i].num=k1;
            e[i].xx=abs(f-double(double(k1)/double(i)));
        }else {
            e[i].len=i;
            e[i].num=k2;
            e[i].xx=abs(f-double(double(k2)/double(i)));
        }
    }
    sort(e+1,e+n+1,cmp);
    for(int k=1;k<=n;k++){
        for(int i=1;i<=n;i++){
            if(sum[i+e[k].len-1]-sum[i-1]==e[k].num){
                ans=i-1;
                cout<<ans<<endl;
                return 0;
            }
        }
    }
    return 0;
}