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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.*;

public class Main {
	
	static class Assert {
		
		static void check(boolean e) {
			if (!e) {
				throw new Error();
			}
		}
	}
	
	static class FastScanner {
        BufferedReader br;
        StringTokenizer st;

        FastScanner(InputStream in) throws IOException {
            br = new BufferedReader(new InputStreamReader(in));
        }

        String next() {
            try {
                while (st == null || !st.hasMoreTokens()) {
                    st = new StringTokenizer(br.readLine());
                }
            } catch (IOException e) {
                System.err.println(e);
                System.exit(1);
            }
            return st.nextToken();
        }

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

        long nextLong() {
            return Long.parseLong(next());
        }
        
    }
	
	FastScanner in;
	
	PrintWriter out;
	
	void solve() throws IOException {
		int n = in.nextInt();
		char[] s = new char[n];
		for (int i = 0; i < n; ++i) {
			s[i] = (char) System.in.read();
		}
		boolean f = false;
		for (int i = 0; i < n - 3; ++i) {
			if ((char) s[i] != '*')
				continue;
			for (int j = i + 1; j < n - 2; ++j) {
				if ((char) s[j] != '*')
					continue;
				for (int p = j + 1; p < n - 1; ++p) {
					if ((char) s[p] != '*')
						continue;
					for (int z = p + 1; z < n; ++z) {
						if ((char) s[z] != '*') 
							continue;
						if (j - i == p - j && z - p == p - j)
							f = true;
					}
				}
			}
		}
		if (f) {
			out.println("yes");
		} else {
			out.println("no");
		}
	}
	
	void run() throws IOException {
		try {
			in = new FastScanner(System.in);
			out = new PrintWriter(System.out);
			//in = new Scanner(new FileReader("input.txt"));
			//out = new PrintWriter(new FileWriter("output.txt"));
		} catch (IOException e) {
			throw new Error(e);
		}
		try {
			solve();
		} finally {
			out.close();
		}
	}
	
	public static void main(String args[]) throws IOException {
		new Main().run();
	}
}