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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.*;

import static java.lang.Math.*;

public class A {
    public void run() throws IOException {
        in = new FastScanner(System.in);
        out = new PrintWriter(System.out);

        int n = in.nextInt();
        char[] c = in.next().toCharArray();

        boolean ans = false;
        for (int s = 0; s < n; s++) {
            for (int d = 1; d < n; d++) {
                if (s + 4 * d < n) {
                    boolean ok = true;
                    for (int k = 0; k < 5; k++) {
                        if (c[s + d * k] != '*') {
                            ok = false;
                        }
                    }
                    if (ok) {
                        ans = true;
                    }
                }
            }
        }

        out.println(ans ? "yes" : "no");

        out.close();
    }

    FastScanner in;
    PrintWriter out;

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

    static class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        FastScanner(InputStream in) throws IOException {
            br = new BufferedReader(new InputStreamReader(in));
        }

        String next() {
            try {
                while (st == null || !st.hasMoreTokens()) {
                    st = new StringTokenizer(br.readLine());
                }
            } catch (IOException e) {
                System.err.println(e);
                System.exit(1);
            }
            return st.nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }
    }
}