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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.*;
import java.util.StringTokenizer;

/**
 * Created by timur on 28.03.15.
 */

public class TaskA {
    boolean eof;
    BufferedReader br;
    StringTokenizer st;
    PrintWriter out;

    public static void main(String[] args) throws IOException {
        new TaskA().run();
    }

    public String nextToken() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (Exception e) {
                eof = true;
                return "-1";
            }
        }
        return st.nextToken();
    }

    public int nextInt() {
        return Integer.parseInt(nextToken());
    }

    public long nextLong() {
        return Long.parseLong(nextToken());
    }

    double nextDouble() {
        return Double.parseDouble(nextToken());
    }

    String nextLine() throws IOException {
        return br.readLine();
    }


    void run() throws IOException {
        InputStream input = System.in;
        PrintStream output = System.out;
        /*String name = "refrain";
        try {
            File f = new File(name + ".in");
            if (f.exists() && f.canRead()) {
                input = new FileInputStream(f);
                output = new PrintStream(name + ".out");
            }
        } catch (Throwable e) {
        }*/
        br = new BufferedReader(new InputStreamReader(input));
        out = new PrintWriter(output);
        solve();
        br.close();
        out.close();
    }

    void solve() {
        int n = nextInt();
        String s = nextToken();
        boolean ok = false;
        for (int i = 0; i < n; i++) {
            for (int j = 0; j < n; j++) {
                if (i + j * 4 < n) {
                    if (s.charAt(i) == '*') {
                        if (s.charAt(i + j) == '*') {
                            if (s.charAt(i + j + j) == '*') {
                                if (s.charAt(i + j+ j + j) == '*') {
                                    if (s.charAt(i + j + j + j + j) == '*') {
                                        ok = true;
                                    }
                                }
                            }

                        }
                    }
                }
            }
        }
        if (ok) {
            out.print("yes");
        } else {
            out.print("no");
        }
    }
}
