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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.io.FileNotFoundException;
import java.util.Scanner;

public class Main {

    public static void main(String args[]) throws FileNotFoundException {
        Scanner in = new Scanner(System.in);
        int n = in.nextInt();
        String maze = in.next();
        boolean good = false;
        for (int i = 0; i < maze.length() && !good; i++) {
            if (maze.charAt(i) != '*')
                continue;

            for (int j = 1; j < maze.length() && !good; j++) {
                int k;
                for (k = 1; k < 5 && (i + (k * j)) < n; k++) {
                    if (maze.charAt(i + (j * k)) != '*')
                        break;

                }
                if (k == 5)
                    good = true;
            }
        }
        System.out.println((good) ? "yes" : "no");

    }

}