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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.BufferedReader;
import java.io.InputStreamReader;
import java.nio.charset.StandardCharsets;
import java.util.StringTokenizer;

public class con526_A {

	static int MB = 1 << 20;
	static BufferedReader br = new BufferedReader(new InputStreamReader(
			System.in, StandardCharsets.US_ASCII), 10 * MB);
	static StringTokenizer st;

	static String NL() throws Exception {
		String s = br.readLine();
		st = new StringTokenizer(s);
		return s;
	}

	static String NT() {
		return st.nextToken();
	}

	public static void main(String[] args) throws Exception {
		NL();
		int N = Integer.parseInt(NT());
		char[] ca = NL().toCharArray();
		boolean good = false;
		outer:
		for (int l = 1; l <= N; l++) {
			for (int f = 0; f + 4 * l < N; f++) {
				if (ca[f] == '*' && ca[f+l] == '*' && ca[f + 2 * l] == '*' && ca[f + 3*l] == '*' && ca[f + 4*l] == '*') {
					good = true;
					break outer;
				}
			}
		}
		System.out.println(good? "yes" : "no ");
	}

}
