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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 javafx.util.Pair;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.*;

public class Main {
    public static void main(String[]args){ConsoleIO io=new ConsoleIO();new Main(io).solve();io.flush();}
    ConsoleIO io;
    Main(ConsoleIO io) {this.io = io;}

    public void solve() {
        int n = io.readInt();
        char[] c = io.readLine().toCharArray();
        for (int s = 1; s < 28; s++) {
            for (int q = 0; q + s + s + s + s < c.length; q++) {
                if (c[q] == '*' && c[q + s] == '*' && c[q + s + s] == '*' && c[q + s + s + s] == '*' && c[q + s + s + s + s] == '*') {
                    io.writeLine("yes");
                    return;
                }
            }
        }
        io.writeLine("no");
    }

}

class ConsoleIO {
    BufferedReader br;
    PrintWriter out;
    public ConsoleIO(){br = new BufferedReader(new InputStreamReader(System.in));out = new PrintWriter(System.out);}
    public void flush(){
        this.out.close();
    }
    public void writeLine(String s) {
        this.out.println(s);
    }
    public void writeInt(int a) {this.out.print(a);this.out.print(' ');}
    public void writeWord(String s){
        this.out.print(s);
    }
    public String readLine() {try {return br.readLine();}catch (Exception ex){ return "";}}
    public long readLong() {
        return Long.parseLong(this.readLine());
    }
    public int readInt() {
        return Integer.parseInt(this.readLine());
    }
    public int[] readIntArray() {
        String[]n=this.readLine().split(" ");int[]r=new int[n.length];
        for(int i=0;i<n.length;i++)r[i]=Integer.parseInt(n[i]);
        return r;
    }
}

