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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.OutputStream;
import java.io.PrintWriter;
import java.util.InputMismatchException;
import java.io.IOException;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		TaskA solver = new TaskA();
		solver.solve(1, in, out);
		out.close();
	}
}

class TaskA {
	public void solve(int testNumber, InputReader in, PrintWriter out) {
		int n = in.nextInt();
		char[] s = in.next().toCharArray();
		for (int i = 0; i < n; i++) {
			for (int len = 1; len <= n; len++) {
				int cnt = 0;
				for (int j = i; j < n; j += len) {
					if (s[j] == '.')
						break;
					++cnt;
					if (cnt == 5) {
						out.println("yes");
						return;
					}
				}
			}
		}
		out.println("no");
	}
}

class InputReader {
	final InputStream is;
	final byte[] buf = new byte[1024];
	int pos;
	int size;

	public InputReader(InputStream is) {
		this.is = is;
	}

	public int nextInt() {
		int c = read();
		while (isWhitespace(c))
			c = read();
		int sign = 1;
		if (c == '-') {
			sign = -1;
			c = read();
		}
		int res = 0;
		do {
			if (c < '0' || c > '9')
				throw new InputMismatchException();
			res = res * 10 + c - '0';
			c = read();
		} while (!isWhitespace(c));
		return res * sign;
	}

	public String next() {
		int c = read();
		while (isWhitespace(c))
			c = read();
		StringBuilder sb = new StringBuilder();
		do {
			sb.append((char) c);
			c = read();
		} while (!isWhitespace(c));
		return sb.toString();
	}

	int read() {
		if (size == -1)
			throw new InputMismatchException();
		if (pos >= size) {
			pos = 0;
			try {
				size = is.read(buf);
			} catch (IOException e) {
				throw new InputMismatchException();
			}
			if (size <= 0)
				return -1;
		}
		return buf[pos++] & 255;
	}

	static boolean isWhitespace(int c) {
		return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
	}

}

