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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 Scanner {
		
		StreamTokenizer in;
		
		Scanner(Reader r) {
			in = new StreamTokenizer(new BufferedReader(r));
			in.resetSyntax();
			in.whitespaceChars(0, 32);
			in.wordChars(33, 255);
		}
		
		String next() {
			try {
				in.nextToken();
				Assert.check(in.ttype == in.TT_WORD);
				return in.sval;
			} catch (IOException e) {
				throw new Error(e);
			}
		}
		
		int nextInt() {
			return Integer.parseInt(next());
		}
		
	}

	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;
	
	//Scanner in;

	PrintWriter out;
	
	void solve() {
		int n = in.nextInt();
		char s[] = in.next().toCharArray();
		boolean f = false;
		for (int i = 0; i < n - 4; ++i) {
			if (s[i] != '*') {
				continue;
			}
			for (int j = i + 1; j < n - 3; ++j) {
				if (s[j] != '*') {
					continue;
				}
				for (int p = j + 1; p < n - 2; ++p) {
					if (s[p] != '*') {
						continue;
					}
					for (int z = p + 1; z < n - 1; ++z) {
						if (s[z] != '*') {
							continue;
						}
						for (int x = z + 1; x < n; ++x) {
							if (s[x] != '*') {
								continue;
							}
							if (x - z == z - p && z - p == p - j && p - j == j - i) {
								f = true;
							}
						}
					}
				}
			}
		}
		out.println(f ? "yes" : "no");
	}
	
	void run() {
		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[]) {
		new Main().run();
	}
}