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****.

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.*;
import java.lang.*;
import java.math.*;

import static java.lang.Math.*;

public class Main implements Runnable {
    
    void solve() throws Exception {
           int n = sc.nextInt();
           char c[] = sc.nextToken().toCharArray();
           for(int i = 0; i < n; i++){
               if(c[i] == '*'){
                   for(int j = 1; j < n; j++){
                       char t = '*';
                       if(j*4 + i < n && c[i+j] == t && c[2*j+i] == t && c[j*3 + i] == t && c[j*4 + i] == t){
                           out.println("yes");
                           return;
                       }
                   }
               }
           }
           out.println("no");
        }
     
    BufferedReader in;
    PrintWriter out;
    FastScanner sc;
    
    static Throwable throwable;
    
    public static void main(String[] args) throws Throwable {
        Thread thread = new Thread(null, new Main(), "", (1 << 26));
        thread.start();
        thread.join();
        thread.run();
        if (throwable != null)
            throw throwable;
    }
    
    
    public void run() {
        try {
            //in = new BufferedReader(new FileReader(".in"));
            //out = new PrintWriter(new FileWriter(".out"));
            in = new BufferedReader(new InputStreamReader(System.in));
            out = new PrintWriter(System.out);
            sc = new FastScanner(in);
            solve();
        } catch (Exception e) {
            throwable = e;
        } finally {
            out.close();
        }
    }
}

class FastScanner {
    BufferedReader reader;
    StringTokenizer strTok;
    
    FastScanner(BufferedReader reader) {
        this.reader = reader;
    }
    
    public String nextToken() throws Exception {
        while (strTok == null || !strTok.hasMoreTokens())
            strTok = new StringTokenizer(reader.readLine());
        return strTok.nextToken();
    }
    
    public int nextInt() throws Exception {
        return Integer.parseInt(nextToken());
    }
    
    public long nextLong() throws Exception {
        return Long.parseLong(nextToken());
    }
    
    public double nextDouble() throws Exception {
        return Double.parseDouble(nextToken());
    }
}
