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***************************************************************************************************
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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 TaskA {
    private FastScanner in;
    private PrintWriter out;

    public void solve() throws IOException {
        int n = in.nextInt();
        char[] s = in.next().toCharArray();
        for (int i = 1; i < 10 * n; i++) {
            for (int j = 0; j < n; j++) {
                boolean ok = true;
                for (int k = 0; k < 5; k++) {
                    int index = j + k * i;
                    if (index >= n || s[index] != '*') {
                        ok = false;
                    }
                }
                if (ok) {
                    out.println("yes");
                    return;
                }
            }

        }
        out.println("no");

    }

    public void run() {
        try {
            in = new FastScanner();
            out = new PrintWriter(System.out);
            solve();
            out.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private class FastScanner {
        private BufferedReader br;
        private StringTokenizer st;

        public FastScanner() {
            br = new BufferedReader(new InputStreamReader(System.in));
        }

        public String next() {
            while (st == null || !st.hasMoreTokens()) {
                try {
                    st = new StringTokenizer(br.readLine());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
            return st.nextToken();
        }

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

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

        public double nextDouble() {
            return Double.parseDouble(next());
        }

    }

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