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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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class A {
	static InputStreamReader isr = new InputStreamReader(System.in);
	static BufferedReader br = new BufferedReader(isr);

	static int[] readIntArray() throws IOException {
		String[] v = br.readLine().split(" ");
		int[] ans = new int[v.length];

		for (int i = 0; i < ans.length; i++) {
			ans[i] = Integer.valueOf(v[i]);
		}

		return ans;
	}

	static int n;
	static char[] l;

	public static void main(String[] args) throws IOException {
		n = readIntArray()[0];
		l = br.readLine().toCharArray();

		boolean ok = false;
		for (int dist = 1; dist <= 30 && !ok; dist++) {
			for (int start = 0; start < n && !ok; start++) {
				boolean current = true;
				for (int i = 0; i < 5; i++) {
					int pos = start + dist * i;
					current = current && (pos < n && l[pos] == '*');
				}
				ok = ok || current;
			}
		}

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

}
