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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.*;
//harish reddy
public class Main
{
    public static void main (String[] args) throws java.lang.Exception
    {
        BufferedReader br = new BufferedReader (new InputStreamReader(System.in));
        PrintWriter pw = new PrintWriter (new BufferedOutputStream(System.out));
        int n = Integer.parseInt(br.readLine());
        String z = br.readLine();
        ArrayList<Integer> arr = new ArrayList<Integer>();
        for(int i =0;i<n;i++){
            char c = z.charAt(i);
            if(c=='*'){
                arr.add(i+1);
            }
        }
        int flag = 0;
        for(int j =0;j<arr.size();j++){
            int count =0 ;
            int k = arr.get(j);
            for(int i =1;i<20;i++){
                if(arr.contains(k+i)){
                    count++;
                    k = k+i;
                }
                else{
                    break;
                }
            }
            if(count>=4){
                flag=1;
            }
        }
        if(flag==1){
            pw.println("yes");
        }
        else{
            pw.println("no");
        }
        pw.close();
    }
}