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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.*;
import java.io.*;
public class Zeptolab_a {
    public static void main(String[] args) throws IOException {
        InputStreamReader isr = new InputStreamReader(System.in);
        Scanner scr = new Scanner(isr);
        int n = scr.nextInt();
        String s = scr.next();
        char [] c = s.toCharArray();
        int t = 0;
        int k = 0;
        f: for (int i = 0; i < n; i++) {
            if (c[i] != '*') continue;
                for (int r = 1; r+i < n; r++) {
                    t = 0;
                    k = 1;
                    while (i+r*k < n) {
                        if (c[i+r*k] == '*') {
                            t++;
                            k++;
                        } else break;
                        if (t == 4) {
                            break f;
                        }
                    }
                }
        }
        PrintWriter pw = new PrintWriter(System.out);
        if (t == 4) {
            pw.print("yes");
        } else pw.print("no");
        pw.flush();
        pw.close();
    }
}