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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.*;

public class Main {
	FastScanner in;
	PrintWriter out;

	void solve() {
		int n = in.nextInt();
		char[] c = in.next().toCharArray();
		for (int st = 0; st < n; st++) {
			for (int len = 1; st + 4 * len < n; len++) {
				boolean ok = true;
				for (int k = 0; k < 5; k++) {
					if (c[st + len * k] == '.')
						ok = false;
				}
				if (ok) {
					out.println("yes");
					return;
				}
			}
		}
		out.println("no");
	}

	void run() {
		in = new FastScanner();
		out = new PrintWriter(System.out);

		solve();

		out.close();
	}

	class FastScanner {
		BufferedReader br;
		StringTokenizer st;

		public FastScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreTokens()) {
				try {
					st = new StringTokenizer(in.br.readLine());
				} catch (IOException e) {
					// TODO Auto-generated catch block
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

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

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

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

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