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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.*;

public class Solution {
    StringTokenizer st;
    BufferedReader in;
    PrintWriter out;

    void solve() throws IOException {
        //in = new BufferedReader(new InputStreamReader(new FileInputStream("input.txt"), "ISO-8859-1"));
        //out = new PrintWriter(new OutputStreamWriter(new FileOutputStream("output.txt"), "ISO-8859-1"));

        in = new BufferedReader(new InputStreamReader(System.in));
        out = new PrintWriter(new OutputStreamWriter(System.out));
        Locale.setDefault(Locale.ENGLISH);

        int n = nextInt();
        String s = in.readLine();

        for (int i = 1; i <= n; i++) {
            for (int j = 0; j + 4 * i < n; j++) {
                if (s.charAt(j) == '*' && s.charAt(j + i) == '*' &&
                        s.charAt(j + 2 * i) == '*' && s.charAt(j + 3 * i) == '*' &&
                        s.charAt(j + 4 * i) == '*') {
                    out.print("yes");
                    out.close();
                    return;
                }
            }
        }

        out.print("no");

        in.close();
        out.close();
    }

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

    String next() throws IOException {
        while (st == null || !st.hasMoreTokens()) {
            st = new StringTokenizer(in.readLine());
        }
        return st.nextToken();
    }

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

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

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