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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.util.Scanner;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.io.InputStreamReader;
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;
		InputStreamReader in = new InputStreamReader(inputStream);
		PrintWriter out = new PrintWriter(outputStream);
		TaskA solver = new TaskA();
		solver.solve(1, in, out);
		out.close();
	}
}

class TaskA {
    public void solve(int testNumber, InputStreamReader in, PrintWriter out) {
        final Scanner scanner = new Scanner(in);
        final int n = Integer.parseInt(scanner.nextLine());
        final String level = scanner.nextLine().trim();
        int offset = 0;

        while (offset + 5 <= level.length()) {
            int jump = 1;

            while (offset + 5 * jump <= level.length()) {
                if ('*' == level.charAt(offset)
                        && '*' == level.charAt(offset + 1 * jump)
                        && '*' == level.charAt(offset + 2 * jump)
                        && '*' == level.charAt(offset + 3 * jump)
                        && '*' == level.charAt(offset + 4 * jump)) {
                    out.println("yes");
                    return;
                }

                jump++;
            }

            offset++;
        }

        out.println("no");
    }
}

