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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.HashSet;
import java.util.LinkedList;
import java.util.Scanner;

public class zepto2015A {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);

		int n = Integer.parseInt(sc.nextLine());
		String s = sc.nextLine();

		HashSet<Integer> h = new HashSet<>();
		LinkedList<Integer> l = new LinkedList<>();

		boolean found = false;

		for (int i = 0; i < n; i++) {
			if (s.charAt(i) == '*') {
				l.add(i);
				h.add(i);
			}
		}

		for (int j = 1; j < n; j++) {

			for (int i = 0; i < l.size(); i++) {
				int cur = l.get(i);

				int step = j;

				for (int jumps = 1; jumps < 5; jumps++) {
					if (h.contains(cur + step))
						step += j;
					else
						break;

					if (jumps == 4)
						found = true;
				}
			}

		}
		System.out.println(found ? "yes" : "no");
	}
}
