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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 javax.swing.*;

/**
 * Created by Shibly Workstation on 24-Dec-16.
 */

/*
public class Main {

    public JFrame frame;

    public Main() {

        frame = new JFrame("Car Game");
        frame.setLocation(250,250);
        frame.setSize(600,700);




        frame.setVisible(true);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setLayout(null);
        frame.setLocationRelativeTo(null);



    }
}
*/



import java.awt.geom.AffineTransform;
import java.awt.image.AffineTransformOp;
import java.awt.image.BufferedImage;
import java.util.Scanner;

public class Main {


        public static void main(String args[]) {

            Scanner scan = new Scanner(System.in);
            int n =scan.nextInt();
            int i,j,k,l,res=0;
            String s= scan.next();
            for( i = 0;i<n;i++){
                if(s.charAt(i)=='.') {


                    for (j = 1; j < n; j++) {
                        k = 1;
                        for ( l = i + j; l < n; l = l+ j)
                            if (s.charAt(l) == '*') {
                                k++;
                            } else {
                                break;
                            }
                        if (k >= 5) {
                            System.out.println("yes");
                            res=1;
                            break;
                        }

                        if (res==1){
                            break;
                        }
                    }

                }
                if (res==1){
                    break;
                }
            }
            if (res==0){
                System.out.println("no");
            }


        }
    }
