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***************************************************************************************************
 5
****.

no yes no no no yes yes no yes yes yes yes yes yes no yes yes yes yes yes yes yes yes yes yes yes no no no yes yes yes yes no no yes yes yes yes yes no yes yes no no no yes yes no yes yes no no no yes yes yes yes no yes yes yes no
import java.util.*;
import java.io.*;
public class Solution
{
    FastScanner in;
    public Solution()
    {
        in=new FastScanner(System.in);
    }

    public static void main(String[] args)
    {
        new Solution().start();
    }

    public void start()
    {
        int n=in.nextInt();
        String str=in.next();
        for(int i=1;i<=n/4;i++)
        {
            for(int j=0;((j+i*4)<n?true:false);j++)
            {
                if(str.charAt(j)=='*' && str.charAt(j+i)=='*' && str.charAt(j+2*i)=='*' && str.charAt(j+3*i)=='*' && str.charAt(j+4*i)=='*')
                {
                    System.out.println("yes");
                    System.exit(0);
                }
            }
        }
        System.out.println("no");
    }
    
  
   
    class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        public FastScanner(File f) {
            try {
                br = new BufferedReader(new FileReader(f));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }

        public FastScanner(InputStream f) {
            br = new BufferedReader(new InputStreamReader(f));
        }

        String next() {
            while (st == null || !st.hasMoreTokens()) {
                String s = null;
                try {
                    s = br.readLine();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (s == null)
                    return null;
                st = new StringTokenizer(s);
            }
            return st.nextToken();
        }

        boolean hasMoreTokens() {
            while (st == null || !st.hasMoreTokens()) {
                String s = null;
                try {
                    s = br.readLine();
                } catch (IOException e) {
                    e.printStackTrace();
                }
                if (s == null)
                    return false;
                st = new StringTokenizer(s);
            }
            return true;
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        double nextDouble() {
            return Double.parseDouble(next());
        }
    }
}
