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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.InputStream;
import java.io.InputStreamReader;
import java.io.BufferedReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.IOException;
import java.util.StringTokenizer;

public class Sample {
    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task solver = new Task();
        solver.solve(in, out);
        out.close();
    }
}

class Task {

    public void solve(InputReader in, PrintWriter out) {
        int n = in.nextInt();
        int a[] = new int [n];
        String s = in.nextLine();
        for (int i=0;i<n;i++) {
            a[i] = s.charAt(i) == '*' ? 1: 0;
        }
        boolean found = false;

        for (int i=0;i<(n/4) && !found;i++) {
            int b[] = new int  [n];
            for (int j=i;j<n;j++) {
                if (a[j - i] == 1) b[j] = b[j-i] + 1;
                if (b[j] == 4) {
                    found = true;
                    break;
                }
            }
        }

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

class InputReader {
    public BufferedReader reader;
    public StringTokenizer tokenizer;

    public InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream), 32768);
        tokenizer = null;
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

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

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

    public String nextLine() {
        try {
            tokenizer = null;
            return reader.readLine();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }
    }

}