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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 RCC {

	Scanner in;
	static PrintWriter out;

	

	void solve() {
		int n = in.nextInt();
		char []s = in.next().toCharArray();
		for (int start = 0; start < n; start++) {
			for (int step = 1; step + start < n; step++) {
				
				int count = 0;
				for (int pos = start; pos < n; pos += step) {
					if (s[pos] != '*') {
						break;
					} else {
						count++;
					}
				}
				if (count >= 5) {
					out.println("yes");
					return;
				}
				
			}
		}
		out.println("no");
	}

	<T> void printArr(T a[]) {
		for (int i = 0; i < a.length; i++) {
			out.print(a[i] + " ");
		}
		out.println();
	}

	static void asserT(boolean e) {
		if (!e) {
			throw new Error();
		}
	}

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

		try {
			solve();
		} finally {
			out.close();
		}
	}

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