import java.util.*;
import java.lang.*;
import java.io.*;

public class Main
{
    public static void main (String[] args) throws java.lang.Exception
    {
        //your code here
      Scanner sc=new Scanner(System.in);
      int n=sc.nextInt();
      int a[]=new int[n];
      for(int i=0;i<n;i++)
        {
          a[i]=sc.nextInt();
        }
      int b=sc.nextInt();
      int c,ind=0,ind1=0,ind2=0,ind3=0,ind4=0,count,count1=Integer.MIN_VALUE;
      int u=0;
      for(int i=0;i<n;i++)
        {
          if(a[i]==0)
          {
            c=0;
            for(int j=i;j<n;j++)
              {
                if(c==b)
                break;
                if(a[j]==0)
                {
                  u++;
                  c++;
                  ind1=j;
                }
              }
              if(c<=b)
              {
                ind=i-1;
                ind2=ind1+1;
                ind3=i;
                ind4=ind1;
                while(ind>=0)
                {
                 if(a[ind]==0)
                  break;
                 else
                  ind3=ind;
                 ind--;
                }
                while(ind2<=(n-1))
               {
                 if(a[ind2]==0)
                   break;
                 else
                  ind4=ind2;
                ind2++;
               }
              count=ind4-ind3+1;
              if(count>count1)
              {
               count1=count;
              }
             }
        }
        }
      if(u>0)
      System.out.println(count1);
      else System.out.println(n);
    }
}