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

public class A implements Runnable {
	private static BufferedReader in;
	private static PrintWriter out;
	private static StringTokenizer st;
	private static Random rnd;

	private void solve() throws IOException {
		int lineLength = nextInt();
		char[] line = nextToken().toCharArray();
		boolean result = false;
		for (int i = 0; i < lineLength; i++) {
			for (int j = 1; j <= lineLength; j++) {
				boolean ok = true;
				for (int k = 0; k <= 4; k++) {
					int pos = i + j * k;
					if (pos < lineLength && line[pos] == '*')
						;
					else
						ok = false;
				}
				if (ok) {
					result = true;
				}
			}
		}
		out.println(result ? "yes" : "no");
	}

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

	public void run() {
		try {
			final String className = this.getClass().getName().toLowerCase();

			try {
				in = new BufferedReader(new FileReader(className + ".in"));
				out = new PrintWriter(new FileWriter(className + ".out"));
				// in = new BufferedReader(new FileReader("input.txt"));
				// out = new PrintWriter(new FileWriter("output.txt"));
			} catch (FileNotFoundException e) {
				in = new BufferedReader(new InputStreamReader(System.in));
				out = new PrintWriter(System.out);
			}

			rnd = new Random();

			solve();

			out.close();
		} catch (IOException e) {
			e.printStackTrace();
			System.exit(42);
		}
	}

	private String nextToken() throws IOException {
		while (st == null || !st.hasMoreTokens()) {
			String line = in.readLine();

			if (line == null)
				return null;

			st = new StringTokenizer(line);
		}

		return st.nextToken();
	}

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

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

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