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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.Scanner;

/**
 * Created by alya on 4/4/15.
 */
public class A {

    private static int N;
    private static String LINE;

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);


        // считывание данных
        N = in.nextInt();

        //int[] lens = new int[N];

        LINE = in.next();

        /*for (int r = 0; r < N; r++) {
            //System.out.println(r);
            lens[r] = in.nextInt();
        }
        */


        boolean b = false;
        int cur_count = 0;
        int maxStep = (N - 1)/4;
        for (int i = 1; i <= maxStep; i++)
        {
            if (b) break;
            for (int s = 0; s < maxStep; s++) {
                cur_count = 0;
                for (int j = s; j < N; j += i) {
                    //System.out.println(i + "," + j + " ");

                    if (LINE.charAt(j) == '*') {
                        cur_count++;
                        //System.out.println("+");
                    } else {
                        cur_count = 0;
                        //System.out.println("-");
                    }

                    if (cur_count == 5) {
                        b = true;
                        break;
                    }
                }
            }
        }










        if (b)
            System.out.println("yes");
        else
            System.out.println("no");

    }

    private static void findSolution()
    {

    }

}
