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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.ArrayList;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;
import java.util.Queue;
import java.util.Scanner;

public class A {
    public static void main(String[] args) throws FileNotFoundException {
        Scanner scan = new Scanner(System.in);
        int n = scan.nextInt();
        String s = scan.next();
        int start = s.indexOf('*');
        if (start == -1) {
            System.out.println("no");
            System.exit(0);
        }
        while (start != -1) {
            for (int i = 1; i < n; i++) {
                boolean w = true;
                int it = 0;
                int c = i;
                while (true) {
                    it++;
                    if (start + c >= n || s.charAt(start + c) != '*') {
                        //System.out.println(start + " " + i);
                        w = false;
                        break;
                    }
                    c = c + i;
                    if (it == 4)
                        break;
                }
                if (w) {
                    System.out.println("yes");
                    System.exit(0);
                }
                // System.out.println(start);
            }
            start = s.indexOf('*', start + 1);
        }
        System.out.println("no");
    }
}