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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.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.io.*;
import java.math.*;
import java.text.*; 
import java.util.*;
import java.util.regex.*;

/*
	  br = new BufferedReader(new FileReader("input.txt"));
	  pw = new PrintWriter(new BufferedWriter(new FileWriter("output.txt")));
	  br = new BufferedReader(new InputStreamReader(System.in));
	  pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
 */


public class Main {
	private static BufferedReader br;
	private static StringTokenizer st;
	private static PrintWriter pw;

	public static void main(String[] args) throws IOException {
		br = new BufferedReader(new InputStreamReader(System.in));
		pw = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
		//int qq = 1;
		int qq = Integer.MAX_VALUE;
		//int qq = readInt();
		for(int casenum = 1; casenum <= qq; casenum++) {
			nextToken();
			String s = nextToken();
			boolean ret = false;
			for(int i = 0; i < s.length(); i++) {
				for(int diff = 1; i + 4 * diff < s.length(); diff++) {
					int count = 0;
					for(int a = 0; a <= 4; a++) {
						if(s.charAt(i + diff * a) == '*') count++;
					}
					ret |= count == 5;
				}
			}
			pw.println(ret ? "yes" : "no");
		}
		exitImmediately();
	}

	private static void exitImmediately() {
		pw.close();
		System.exit(0);
	}

	private static long readLong() throws IOException {
		return Long.parseLong(nextToken());
	}

	private static double readDouble() throws IOException {
		return Double.parseDouble(nextToken());
	}

	private static int readInt() throws IOException {
		return Integer.parseInt(nextToken());
	}

	private static String nextLine() throws IOException  {
		if(!br.ready()) {
			exitImmediately();
		}
		st = null;
		return br.readLine();
	}

	private static String nextToken() throws IOException  {
		while(st == null || !st.hasMoreTokens())  {
			if(!br.ready()) {
				exitImmediately();
			}
			st = new StringTokenizer(br.readLine().trim());
		}
		return st.nextToken();
	}
}
