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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.*;
import java.util.StringTokenizer;
import java.util.TreeMap;

public class KingOfThieves {
	public static void main(String[] args) throws IOException, InterruptedException {
		Scanner sc = new Scanner(System.in);
		PrintWriter pw = new PrintWriter(System.out);
		TreeMap<Integer, Integer> map = new TreeMap<>();
		int n = sc.nextInt();
		char c[] = sc.nextLine().toCharArray();
		for (int i = 0; i < c.length; i++) {
			if (c[i] == '*') {
				for (int j = i + 1; j < c.length; j++) {
					if (c[j] == '*') {
						int x = j - i;
						if (map.containsKey(x)) {
							int z = map.get(x);
							map.replace(x, z + 1);
							if (z == 3) {
								pw.println("yes");
								pw.flush();
								return;
							}
						} else
							map.put(x, 1);
					}
				}
			}
		}
		pw.println("no");
		pw.flush();
	}

	static class Scanner {
		StringTokenizer st;
		BufferedReader br;

		public Scanner(InputStream system) {
			br = new BufferedReader(new InputStreamReader(system));
		}

		public String next() throws IOException {
			while (st == null || !st.hasMoreTokens())
				st = new StringTokenizer(br.readLine());
			return st.nextToken();
		}

		public String nextLine() throws IOException {
			return br.readLine();
		}

		public int nextInt() throws IOException {
			return Integer.parseInt(next());
		}

		public double nextDouble() throws IOException {
			return Double.parseDouble(next());
		}

		public char nextChar() throws IOException {
			return next().charAt(0);
		}

		public Long nextLong() throws IOException {
			return Long.parseLong(next());
		}

		public boolean ready() throws IOException {
			return br.ready();
		}

		public void waitForInput() throws InterruptedException {
			Thread.sleep(4000);
		}
	}
}
