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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.io.*;
import java.util.Scanner;

/**
 * Author: Sergey Paramonov
 * Date: 04.04.15
 * Time: 20:05
 */
public class Zepto_20150404_A {

    Scanner scanner = new Scanner(System.in);
    BufferedReader buffered = new BufferedReader(new InputStreamReader(System.in));
    StreamTokenizer input = new StreamTokenizer(buffered);

    PrintWriter output = new PrintWriter(new BufferedOutputStream(System.out));

    int nextInt() throws Exception {
        input.nextToken();
        return (int) input.nval;
    }

    void flushAndClose() {
        output.flush();
        System.out.flush();
        output.close();
    }

    void main() throws Exception {
        int n = Integer.valueOf(buffered.readLine());
        String s = buffered.readLine();
        boolean bingo = false;
        for (int p = 1; p*4 < n; p++) {
            for (int i = 0; i + 4*p < n; i++) {
                if (s.charAt(i) == '*' && s.charAt(i+p) == '*' && s.charAt(i+2*p) == '*' && s.charAt(i+3*p) == '*' && s.charAt(i+4*p) == '*') {
                    bingo = true;
                    break;
                }
            }
        }
        output.println(bingo ? "yes" : "no");
        flushAndClose();
    }

    public static void main(String[] args) throws Exception {
        new Zepto_20150404_A().main();
    }

}
