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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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class Main {
	static BufferedReader reader;
	static StringTokenizer tokenizer;
	static PrintWriter writer;

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

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

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

	static boolean eof = false;

	static String nextToken() throws IOException {
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			tokenizer = new StringTokenizer(reader.readLine());
		}
		return tokenizer.nextToken();
	}

	public static void main(String[] args) throws IOException {
		tokenizer = null;
		// reader = new BufferedReader(new FileReader("input.txt"));
		// writer = new PrintWriter(new FileWriter("output.txt"));
		reader = new BufferedReader(new InputStreamReader(System.in, "ISO-8859-1"));
		writer = new PrintWriter(System.out);
		banana();
		reader.close();
		writer.close();
	}

	static void banana() throws IOException {
		int n = nextInt();
		boolean ok[] = new boolean[n];

		String s = nextToken();

		for (int i = 0; i < n; ++i) {
			ok[i] = (s.charAt(i) == '*');
		}

		boolean ans = false;

		for (int step = 1; step < n; ++step) {
			for (int j = 0; j < n; ++j) {
				boolean x = true;
				for (int k = 0; k < 5; ++k) {
					x = x && ((j + step * k < n) && ok[j + step * k]);
				}
				ans = ans || x;
			}
		}

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

