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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
/**  _ _
 * \(^.^\)
 *  ( 8 ;)
 *  ( __;)
 *   V  V
 * by Abril
 */

import java.io.*;
import java.util.*;

public class Main {
	
	void solve() {
		int n = in.nextInt();
		String s = in.next();
		boolean respuesta = false;
		for (int i = 0; i < n; i++) {
			if (s.charAt(i) == '*') {
				for (int j = i + 1; j < n; j++) {
					if (s.charAt(j) == '*') {
						int largo = j - i, contador = 1;
						int k = j;
						while (true) {
							if (k + largo < n && s.charAt(k + largo) == '*') {
								k += largo;
								contador++;
							} else {
								break;
							}
						}
						if (contador >= 4) respuesta = true;
					}
				}
			}
		}
		out.println(respuesta ? "yes" : "no");
	}
	
	void run() {
		in = new InputReader(System.in);
		out = new PrintWriter(System.out);
		solve();
		out.close();
	}
	
	InputReader in;
	PrintWriter out;
	
	class InputReader {
		BufferedReader br;
		StringTokenizer st;
		
		InputReader(InputStream is) {
			br = new BufferedReader(new InputStreamReader(is));
			st = null;
		}
		
		String next() {
			while (st == null || !st.hasMoreTokens()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return st.nextToken();
		}
		
		int nextInt() {
			return Integer.parseInt(next());
		}
	}
	
	public static void main(String[] args) {
		new Main().run();
	}
}