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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.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.io.FileReader;
import java.io.IOException;
import java.util.StringTokenizer;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author Agostinho Junior (junior94)
 */
public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		OutputWriter out = new OutputWriter(outputStream);
		TaskA solver = new TaskA();
		solver.solve(1, in, out);
		out.close();
	}
}

class TaskA {

	public void solve(int testNumber, InputReader in, OutputWriter out) {
		int n = in.readInt();
		String s = in.next();
		for (int i = 0; i < n; i++) if (s.charAt(i) == '*') {
			for (int l = 1; i + l < n; l++) {
				int count = 1;
				int pos = i + l;
				while (count < 4) {
					if (pos >= n || s.charAt(pos) == '.') {
						break;
					}
					count++;
					pos += l;
				}
				if (count == 4) {
					out.println("yes");
					return;
				}
			}
		}
		out.println("no");
	}

}

class InputReader {
	private BufferedReader input;
	private StringTokenizer line = new StringTokenizer("");

	public InputReader(InputStream in) {
		input = new BufferedReader(new InputStreamReader(in));
	}

	public void fill() {
		try {
			if(!line.hasMoreTokens()) line = new StringTokenizer(input.readLine());
		} catch(IOException io) { io.printStackTrace(); System.exit(0);}
	}

	public String next() {
		fill();
		return line.nextToken();
	}

	public int readInt() {
		fill();
		return Integer.parseInt(line.nextToken());
	}

}

class OutputWriter {
	private PrintWriter output;

	public OutputWriter(OutputStream out) {
		output = new PrintWriter(out);
	}

	public void println(Object o) {
		output.println(o);
	}

	public void close() {
		output.close();
	}
}

