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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 A {

	BufferedReader in;
	StringTokenizer st;
	PrintWriter out;

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

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

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

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

	void solve() throws Exception {
		int n = nextInt();
		String s = next();
		out.println(checkOk(s));

	}

	private String checkOk(String s) {
		for (int i = 1; i <= s.length(); i++)
			if (check(s, i))
				return "yes";
		return "no";
	}

	private boolean check(String s, int l) {
		String chk = s;
		for (int i = 0; i <= 50; i++)
			chk = chk + "----------";
		for (int i = 0; i < s.length(); i++)
			if (chk.charAt(i) == '*')
				if (chk.charAt(i + l) == '*')
					if (chk.charAt(i + l + l) == '*')
						if (chk.charAt(i + l + l + l) == '*')
							if (chk.charAt(i + l + l + l + l) == '*')
								return true;
		return false;
	}

	void run() {
		try {
			Locale.setDefault(Locale.US);
			in = new BufferedReader(new InputStreamReader(System.in));
			out = new PrintWriter(new OutputStreamWriter(System.out));
			solve();
			out.close();
		} catch (Exception e) {
			e.printStackTrace();
			System.exit(1);
		}
	}

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

}
