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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.util.*;
import java.math.*;
import java.text.*;
import java.io.*;
import java.awt.Point;

import static java.util.Arrays.*;
import static java.lang.Integer.*;
import static java.lang.Double.*;
import static java.lang.Long.*;
import static java.lang.Short.*;
import static java.lang.Math.*;
import static java.math.BigInteger.*;
import static java.util.Collections.*;

public class A {

	// IO Imports
	private Scanner in;
	private StringTokenizer st;
	private PrintWriter out;

	// Pretty Stuff
	private DecimalFormat fmt = new DecimalFormat("0.0000000000");

	public void solve() throws Exception {
		int n = in.nextInt();

		char[] lvl = in.next().toCharArray();

		for (int i=2; i<n/5; i++) {
			// i is start
			for (int j=0; j<n; j++) {
				boolean can = true;
				for (int k = j; k<n; k+=i) {
					if (lvl[k] == '.') {
						can = false;
						break;
					}
				}

				if (can) {
					out.println("yes");
					return;
				}
			}
		}

		out.println("no");
	}

	public A() {
		this.in = new Scanner(System.in);
		this.out = new PrintWriter(System.out);
	}

	public void end() {
		try {
			this.out.flush();
			this.out.close();
			this.in.close();
		} catch (Exception e){
			//do nothing then :)
		}
	}

	public static void main(String[] args) throws Exception {
		A solver = new A();
		solver.solve();
		solver.end();
	}
}
